1
|
Mortvedt-Abildgaa CI, Nissen-Meyer J, Jelle B, Grenov B, Skaugen M, Nes IF. Production and pH-Dependent Bactericidal Activity of Lactocin S, a Lantibiotic from Lactobacillus sake L45. Appl Environ Microbiol 2010; 61:175-9. [PMID: 16534901 PMCID: PMC1388324 DOI: 10.1128/aem.61.1.175-179.1995] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The amount of lactocin S activity in a growing culture depends on the growth stage of the bacteria, the pH of the medium, the presence of ethanol, and the aeration of the culture. We observed the highest levels of bacteriocin activity in the early stationary growth phase of cultures at 30 deg C. When Lactobacillus sake L45 was grown in a fermentor at pH 5, it produced 2,000 to 3,000 bacteriocin units per ml, which represented an 8- to 10-fold increase in bacteriocin production compared with production during batch culture fermentation. Less than 10% of this level of bacteriocin activity was observed during fermentation at pH 6.0. When 1% ethanol was included in the growth medium, a two- to fourfold increase in the bacteriocin yield was observed. Aerating the culture during growth almost completely eliminated the production of active bacteriocin. Our results also showed that lactocin S-mediated killing of target cells depended on the pH of the culture. The pH had to be less than 6 in order to obtain a bactericidal effect with lactocin S-sensitive cells. At pH values greater than 6, lactocin S had no apparent effect on sensitive cells.
Collapse
|
2
|
Peddireddi L, Cheng C, Ganta RR. Promoter analysis of macrophage- and tick cell-specific differentially expressed Ehrlichia chaffeensis p28-Omp genes. BMC Microbiol 2009; 9:99. [PMID: 19454021 PMCID: PMC2694197 DOI: 10.1186/1471-2180-9-99] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2009] [Accepted: 05/19/2009] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Ehrlichia chaffeensis is a rickettsial agent responsible for an emerging tick-borne illness, human monocytic ehrlichiosis. Recently, we reported that E. chaffeensis protein expression is influenced by macrophage and tick cell environments. We also demonstrated that host response differs considerably for macrophage and tick cell-derived bacteria with delayed clearance of the pathogen originating from tick cells. RESULTS In this study, we mapped differences in the promoter regions of two genes of p28-Omp locus, genes 14 and 19, whose expression is influenced by macrophage and tick cell environments. Primer extension and quantitative RT-PCR analysis were performed to map transcription start sites and to demonstrate that E. chaffeensis regulates transcription in a host cell-specific manner. Promoter regions of genes 14 and 19 were evaluated to map differences in gene expression and to locate RNA polymerase binding sites. CONCLUSION RNA analysis and promoter deletion analysis aided in identifying differences in transcription, DNA sequences that influenced promoter activity and RNA polymerase binding regions. This is the first description of a transcriptional machinery of E. chaffeensis. In the absence of available genetic manipulation systems, the promoter analysis described in this study can serve as a novel molecular tool for mapping the molecular basis for gene expression differences in E. chaffeensis and other related pathogens belonging to the Anaplasmataceae family.
Collapse
Affiliation(s)
- Lalitha Peddireddi
- Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506, USA.
| | | | | |
Collapse
|
3
|
Yamazaki Y, Fukusumi H, Kamikubo H, Kataoka M. Role of the N-terminal region in the function of the photosynthetic bacterium transcription regulator PpsR. Photochem Photobiol 2008; 84:839-44. [PMID: 18282179 DOI: 10.1111/j.1751-1097.2008.00306.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PpsR is a transcription repressor for the gene cluster encoding photosystem genes in Rhodobacter sphaeroides. Repression activity is accomplished by DNA binding on the promoter regions of the photosystem gene clusters, and depends on both the redox potential and the presence of antirepressor protein AppA. To understand DNA repression regulation by PpsR, we investigated the function of PpsR domains in self-association for DNA binding. We constructed domain-deletion mutants and verified DNA-binding activity and dimer formation. Gel shift assay for measuring the DNA-binding activity of three sequential N-terminal deletion mutants revealed that N-terminal deletions (of minimum 121 residues) caused loss of binding activity. Size-exclusion gel chromatography revealed that deletion mutant which lacks the N-terminal 121-amino acid deletion mutant to exist as a dimer, although it was less stable than the intact PpsR. The mutants lacking the adjacent regions, Q-linker region and the first Per-Ant-Sim domain, did not form dimers, suggesting the involvement of the N-terminal region in dimer formation. This region is thus considered to be a functional domain in self-association, although not yet identified as a structural domain. Circular dichroism spectrum of the N-terminal region fragment exhibited a alpha/beta structure. We conclude that this region is a structural and functional domain, contributing to PpsR repression through dimer stabilization.
Collapse
Affiliation(s)
- Yoichi Yamazaki
- Graduate School of Materials Science, Nara Institute of Science and Technology, Ikoma, Nara, Japan
| | | | | | | |
Collapse
|
4
|
Kovács AT, Rákhely G, Kovács KL. The PpsR regulator family. Res Microbiol 2005; 156:619-25. [PMID: 15950121 DOI: 10.1016/j.resmic.2005.02.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2005] [Revised: 02/04/2005] [Accepted: 02/04/2005] [Indexed: 10/25/2022]
Abstract
Under aerobic conditions, phototrophic bacteria repress the formation of pigments to protect cells in the presence of light from the damaging effects of reactive oxygen species and consume oxygen through respiratory complexes. Members of the PpsR family regulate the transcription of bch, crt, puc, and hem genes in respond to redox or light conditions. This mini-review focuses on the function and distribution of PpsR proteins.
Collapse
Affiliation(s)
- Akos T Kovács
- Institute of Biophysics, Biological Research Center, Hungarian Academy of Sciences and Department of Biotechnology, University of Szeged, Szeged, Temesvári krt. 62, Hungary
| | | | | |
Collapse
|
5
|
Biel AJ, Canada K, Huang D, Indest K, Sullivan K. Oxygen-mediated regulation of porphobilinogen formation in Rhodobacter capsulatus. J Bacteriol 2002; 184:1685-92. [PMID: 11872720 PMCID: PMC134899 DOI: 10.1128/jb.184.6.1685-1692.2002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2001] [Accepted: 12/05/2001] [Indexed: 11/20/2022] Open
Abstract
A Rhodobacter capsulatus hemC mutant has been isolated and used to show that oxygen regulates the intracellular levels of porphobilinogen. Experiments using a hemB-cat gene fusion demonstrated that oxygen does not transcriptionally regulate hemB transcription. Porphobilinogen synthase activity is not regulated by oxygen nor is the enzyme feedback inhibited by hemin or protoporphyrin IX. It was demonstrated that less than 20% of [(14)C]aminolevulinate was incorporated into bacteriochlorophyll, suggesting that the majority of the aminolevulinate is diverted from the common tetrapyrrole pathway. Porphobilinogen oxygenase activity was not observed in this organism; however, an NADPH-linked aminolevulinate dehydrogenase activity was demonstrated. The specific activity of this enzyme increased with increasing oxygen tension. The results presented here suggest that carbon flow over the common tetrapyrrole pathway is regulated by a combination of feedback inhibition of aminolevulinate synthase and diversion of aminolevulinate from the pathway by aminolevulinate dehydrogenase.
Collapse
Affiliation(s)
- Alan J Biel
- Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana 70803, USA.
| | | | | | | | | |
Collapse
|
6
|
Yamamoto I, Ujiiye T, Ohshima Y, Satoh T. Mutational analysis of regulatory cis-acting elements for the transcriptional activation of the dmsCBA operon in Rhodobacter sphaeroides f. sp. denitrificans. PLANT & CELL PHYSIOLOGY 2001; 42:703-709. [PMID: 11479376 DOI: 10.1093/pcp/pce083] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Four direct repeats of a 10-nt sequence, called dms boxes, are located upstream of the dmsCBA operon encoding dimethyl sulfoxide (DMSO) reductase in Rhodobacter sphaeroides f. sp. denitrificans IL106. Two dms boxes 1 and 2 have been shown to be binding sites of DmsR protein, a response regulator of a two-component system involved in the anaerobic induction by DMSO of DMSO reductase synthesis. In this study, functions of four dms boxes in the transcriptional regulation of the dmsCBA operon were investigated. The transcription start site of the dmsCBA genes was identified at the distance of 23 nt downstream of the closest dms box 4. Expression of the dmsC-lacZ gene fusion which included the dmsCBA promoter region containing the dms boxes was examined and its anaerobic induction by DMSO and DmsR-dependency were demonstrated in the phototroph. The examination with nucleotide substitutions in the four respective dms boxes showed that the set of four dms boxes is required for the dmsCBA operon activation. Moreover, the importance of the nucleotide sequence of TTCAC in dms box 4 and of A at the center in dms box 1 was significantly shown. These facts suggest that the pentad nucleotides TTCAC and TTAAC in the dms boxes serve as cis-acting elements in the transcriptional activation of the dmsCBA operon.
Collapse
Affiliation(s)
- I Yamamoto
- Department of Biological Science, Graduate School of Science, Hiroshima University, Higashi-Hiroshima, 739-8526, Japan.
| | | | | | | |
Collapse
|
7
|
Du S, Kouadio JL, Bauer CE. Regulated expression of a highly conserved regulatory gene cluster is necessary for controlling photosynthesis gene expression in response to anaerobiosis in Rhodobacter capsulatus. J Bacteriol 1999; 181:4334-41. [PMID: 10400592 PMCID: PMC93936 DOI: 10.1128/jb.181.14.4334-4341.1999] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We utilized primer extension analysis to demonstrate that the divergently transcribed regB and senC-regA-hvrA transcripts contain stable 5' ends 43 nucleotides apart within the regB-senC intergenic region. DNA sequence analysis indicates that this region contains two divergent promoters with overlapping sigma70 type -35 and -10 promoter recognition sequences. In vivo analysis of expression patterns of regB::lacZ and senC-regA-hvrA::lacZ reporter gene fusions demonstrates that the regB and senC-regA-hvrA transcripts are both negatively regulated by the phosphorylated form of the global response regulator RegA. DNase I protection assays with a constitutively active variant of RegA indicate that RegA binds between regB and senC overlapping -10 and -35 promoter recognition sequences. Two mutations were also isolated in a regB-deficient background that increased expression of the senC-regA-hvrA operon 10- and 5-fold, respectively. As a consequence of increased RegA expression, these mutants exhibited elevated aerobic and anaerobic photosynthesis (puf) gene expression, even in the absence of the sensor kinase RegB. These results indicate that autoregulation by RegA is a factor contributing to the maintenance of an optimal low level of RegA expression that allows responsiveness to activation by phosphorylation.
Collapse
Affiliation(s)
- S Du
- Department of Biology, Indiana University, Bloomington, Indiana 47405, USA
| | | | | |
Collapse
|
8
|
Bowman WC, Du S, Bauer CE, Kranz RG. In vitro activation and repression of photosynthesis gene transcription in Rhodobacter capsulatus. Mol Microbiol 1999; 33:429-37. [PMID: 10411758 DOI: 10.1046/j.1365-2958.1999.01490.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
It has been known for over half a century that anoxygenic photosynthetic bacteria maximally synthesize their photosystems in the absence of oxygen. During the last decade, it has become clear that this regulation is largely at the transcriptional level, with photosynthesis genes expressed only under anaerobic conditions. We describe here in vitro reconstitution of activation and repression of three photosynthesis promoters, bch (bacteriochlorophyll biosynthesis), puc (light-harvesting II apoproteins) and puf (reaction centre and light-harvesting I apoproteins) using purified transcription factors and RNA polymerase from Rhodobacter capsulatus. Previous genetic results have indicated that each of these three promoters is differentially regulated by three key regulators: CrtJ acting as a repressor of bch and puc and the two-component regulators RegA/RegB, which are activators of puc and puf. These regulators are distinct from those that mediate oxygen control in enteric bacteria. Our in vitro studies show that these purified regulators directly control the expression of the housekeeping RNA polymerase at these promoters. High-level basal expression of the bch promoter is shown to be repressed by CrtJ. The puc promoter is activated by the RegB-phosphorylated RegA protein and additionally repressed by CrtJ. At the puc promoter, CrtJ effectively competes for promoter binding with RegA, while at the bch promoter, repression appears to be by competition for the RNA polymerase binding site. In contrast to what has been suggested previously, the RegA-activated puf promoter is demonstrated as being recognized by the housekeeping RNA polymerase. We also discuss evidence that RegA approximately P activation of the puc and puf promoters involves recruitment of RNA polymerase by different modes of protein-protein interaction.
Collapse
Affiliation(s)
- W C Bowman
- Department of Biology, Washington University, One Brookings Drive, St Louis, MO 63130, USA
| | | | | | | |
Collapse
|
9
|
Page MD, Sockett RE. 13 Molecular Genetic Methods in Paracoccus and Rhodobacter with Particular Reference to the Analysis of Respiration and Photosynthesis. METHODS IN MICROBIOLOGY 1999. [DOI: 10.1016/s0580-9517(08)70124-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
|
10
|
Baker SC, Ferguson SJ, Ludwig B, Page MD, Richter OM, van Spanning RJ. Molecular genetics of the genus Paracoccus: metabolically versatile bacteria with bioenergetic flexibility. Microbiol Mol Biol Rev 1998; 62:1046-78. [PMID: 9841665 PMCID: PMC98939 DOI: 10.1128/mmbr.62.4.1046-1078.1998] [Citation(s) in RCA: 147] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Paracoccus denitrificans and its near relative Paracoccus versutus (formerly known as Thiobacilllus versutus) have been attracting increasing attention because the aerobic respiratory system of P. denitrificans has long been regarded as a model for that of the mitochondrion, with which there are many components (e.g., cytochrome aa3 oxidase) in common. Members of the genus exhibit a great range of metabolic flexibility, particularly with respect to processes involving respiration. Prominent examples of flexibility are the use in denitrification of nitrate, nitrite, nitrous oxide, and nitric oxide as alternative electron acceptors to oxygen and the ability to use C1 compounds (e.g., methanol and methylamine) as electron donors to the respiratory chains. The proteins required for these respiratory processes are not constitutive, and the underlying complex regulatory systems that regulate their expression are beginning to be unraveled. There has been uncertainty about whether transcription in a member of the alpha-3 Proteobacteria such as P. denitrificans involves a conventional sigma70-type RNA polymerase, especially since canonical -35 and -10 DNA binding sites have not been readily identified. In this review, we argue that many genes, in particular those encoding constitutive proteins, may be under the control of a sigma70 RNA polymerase very closely related to that of Rhodobacter capsulatus. While the main focus is on the structure and regulation of genes coding for products involved in respiratory processes in Paracoccus, the current state of knowledge of the components of such respiratory pathways, and their biogenesis, is also reviewed.
Collapse
Affiliation(s)
- S C Baker
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, United Kingdom.
| | | | | | | | | | | |
Collapse
|
11
|
Ponnampalam SN, Elsen S, Bauer CE. Aerobic repression of the Rhodobacter capsulatus bchC promoter involves cooperative interactions between CrtJ bound to neighboring palindromes. J Biol Chem 1998; 273:30757-61. [PMID: 9804852 DOI: 10.1074/jbc.273.46.30757] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Previous studies demonstrated that bacteriochlorophyll, carotenoid, and light harvesting gene expression in Rhodobacter capsulatus is repressed under aerobic growth conditions by the repressor CrtJ. Isolated CrtJ is known to bind to the palindrome TGTN12ACA, which is present in two copies in the bchC promoter, one of which spans the -35 and the other the -10 sigma-70 recognition sequences. In this study, we demonstrate that CrtJ binds to the two palindromic sites in the bchC promoter in a cooperative manner. The level of cooperativity of CrtJ binding to the -35 palindrome was shown to be 26-fold. A distance of 8 base pairs between the two palindromic sites was shown to be critical for cooperative binding, as evidenced by the disruption of binding that resulted when +6 and +11 base pairs were inserted between the palindromes.
Collapse
Affiliation(s)
- S N Ponnampalam
- Biochemistry Program, Department of Chemistry, Indiana University, Bloomington, Indiana 47405, USA
| | | | | |
Collapse
|
12
|
Elsen S, Ponnampalam SN, Bauer CE. CrtJ bound to distant binding sites interacts cooperatively to aerobically repress photopigment biosynthesis and light harvesting II gene expression in Rhodobacter capsulatus. J Biol Chem 1998; 273:30762-9. [PMID: 9804853 DOI: 10.1074/jbc.273.46.30762] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Expression of light harvesting II genes and of bacteriochlorophyll and carotenoid biosynthesis genes in Rhodobacter capsulatus is repressed under aerobic growth conditions by the transcription factor CrtJ. In this study, we demonstrate that the crtA-crtI intergenic region contains divergent promoters that initiate transcription 116 base pairs apart, based on primer extension analyses. DNase I protection assays demonstrate that purified CrtJ binds to one palindrome that overlaps the crtA -10 promoter recognition sequence as well as to a second palindrome that overlaps the -35 crtI promoter recognition sequence. Similar analyses also show that the puc promoter region contains two distant CrtJ palindromes, with one near the -35 promoter recognition sequence and the other located 240 base pairs upstream. Gel mobility shift and filter retention assays indicate that CrtJ binds in a cooperative manner to these distantly separated palindromes. In vivo expression assays with puc and crtI promoter reporter plasmids further demonstrate that aerobic repression of puc and crtI expression requires both CrtJ palindromes. These in vitro and in vivo results indicate that aerobic repression of puc, crtA, and crtI expression involves cooperative interactions between CrtJ bound to distant palindromes. A DNA looping model is discussed.
Collapse
Affiliation(s)
- S Elsen
- Department of Biology, Department of Chemistry, Indiana University, Bloomington, Indiana 47405, USA
| | | | | |
Collapse
|
13
|
Zeilstra-Ryalls JH, Gomelsky M, Yeliseev AA, Eraso JM, Kaplan S. Transcriptional regulation of photosynthesis operons in Rhodobacter sphaeroides 2.4.1. Methods Enzymol 1998; 297:151-66. [PMID: 9750207 DOI: 10.1016/s0076-6879(98)97012-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- J H Zeilstra-Ryalls
- Department of Microbiology and Molecular Genetics, University of Texas Medical School at Houston 77030, USA
| | | | | | | | | |
Collapse
|
14
|
Nickens DG, Bauer CE. Analysis of the puc operon promoter from Rhodobacter capsulatus. J Bacteriol 1998; 180:4270-7. [PMID: 9696778 PMCID: PMC107426 DOI: 10.1128/jb.180.16.4270-4277.1998] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/1998] [Accepted: 06/09/1998] [Indexed: 11/20/2022] Open
Abstract
Expression of the Rhodobacter capsulatus puc operon, which codes for structural polypeptides of the light-harvesting-II peripheral antenna complex, is highly regulated in response to alterations in oxygen tension and light intensity. To obtain an understanding of the puc promoter region we report the high-resolution 5' mapping of the puc mRNA transcriptional start site and DNA sequence analysis of the puc upstream regulatory sequence (pucURS). A sigma70-type promoter sequence was identified (pucP1) which has a high degree of sequence similarity with carotenoid and bacteriochlorophyll biosynthesis promoters. Inspection of the DNA sequence also indicated the presence of two CrtJ and four integration host factor (IHF) binding sites. Transcriptional fusions of the pucURS fused to lacZ also confirmed that puc promoter activity is regulated by the transcriptional regulators IHF, CrtJ, and RegA. Gel retardation analysis using cell extracts indicates that mutations in IHF and RegA disrupt protein binding to DNA fragments containing the pucURS.
Collapse
Affiliation(s)
- D G Nickens
- Department of Biology, Indiana University, Bloomington, Indiana 47405, USA
| | | |
Collapse
|
15
|
Zeilstra-Ryalls J, Gomelsky M, Eraso JM, Yeliseev A, O'Gara J, Kaplan S. Control of photosystem formation in Rhodobacter sphaeroides. J Bacteriol 1998; 180:2801-9. [PMID: 9603864 PMCID: PMC107241 DOI: 10.1128/jb.180.11.2801-2809.1998] [Citation(s) in RCA: 95] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Affiliation(s)
- J Zeilstra-Ryalls
- Department of Microbiology and Molecular Genetics, University of Texas Health Sciences Center-Houston, Houston, Texas 77030, USA
| | | | | | | | | | | |
Collapse
|
16
|
Borghese R, Crimi M, Fava L, Melandri BA. The ATP synthase atpHAGDC (F1) operon from Rhodobacter capsulatus. J Bacteriol 1998; 180:416-21. [PMID: 9440534 PMCID: PMC106900 DOI: 10.1128/jb.180.2.416-421.1998] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The atpHAGDC operon of Rhodobacter capsulatus, containing the five genes coding for the F1 sector of the ATP synthase, has been cloned and sequenced. The promoter region has been defined by primer extension analysis. It was not possible to obtain viable cells carrying atp deletions in the R. capsulatus chromosome, indicating that genes coding for ATP synthase are essential, at least under the growth conditions tested. We were able to circumvent this problem by combining gene transfer agent transduction with conjugation. This method represents an easy way to construct strains carrying mutations in indispensable genes.
Collapse
Affiliation(s)
- R Borghese
- Department of Biology, University of Bologna, Italy
| | | | | | | |
Collapse
|
17
|
Cullen PJ, Kaufman CK, Bowman WC, Kranz RG. Characterization of the Rhodobacter capsulatus housekeeping RNA polymerase. In vitro transcription of photosynthesis and other genes. J Biol Chem 1997; 272:27266-73. [PMID: 9341173 DOI: 10.1074/jbc.272.43.27266] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
To begin to characterize biochemically the transcriptional activation systems in photosynthetic bacteria, the Rhodobacter capsulatus RNA polymerase (RNAP) that contains the sigma70 factor (R. capsulatus RNAP/sigma70) was purified and characterized using two classical sigma70 type promoters, the bacteriophage T7A1 and the RNA I promoters. Transcription from these promoters was sensitive to rifampicin, RNase, and monoclonal antibody 2G10 (directed against the Escherichia coli sigma70 subunit). Specific transcripts were detected in vitro for R. capsulatus cytochrome c2 (cycA) and fructose-inducible (fruB) promoters and genes induced in photosynthesis (puf and puc) and bacteriochlorophyll biosynthesis (bchC). Alignment of these natural promoters activated by R. capsulatus RNAP/sigma70 indicated a preference for the sequence TTGAC at the -35 region for strong in vitro transcription. To test the -35 recognition pattern, the R. capsulatus nifA1 promoter, which exhibits only three of the five consensus nucleotides at the -35 region, was mutated to four and five of the consensus nucleotides. Although the nifA1 wild type promoter showed no transcription, the double mutated promoter exhibited high levels of in vitro transcription by the purified R. capsulatus RNAP/sigma70 enzyme. Similarities and differences between the RNAPs and the promoters of R. capsulatus and E. coli are discussed.
Collapse
Affiliation(s)
- P J Cullen
- Department of Biology, Washington University, St. Louis, Missouri 63130, USA
| | | | | | | |
Collapse
|
18
|
Abstract
A chemotaxis gene cluster from the photosynthetic bacterium Rhodospirillum centenum has been cloned, sequenced, and analyzed for the control of transcription during swimmer-to-swarm cell differentiation. The first gene of the operon (cheAY) codes for a large 108-kDa polypeptide with an amino-terminal domain that is homologous to CheA and a carboxyl terminus that is homologous to CheY. cheAY is followed by cheW, an additional homolog of cheY, cheB, and cheR. Sequence analysis indicated that all of the che genes are tightly compacted with the same transcriptional polarity, suggesting that they are organized in an operon. Cotranscription of the che genes was confirmed by demonstrating through Western blot analysis that insertion of a polar spectinomycin resistance gene in cheAY results in loss of cheR expression. The promoter for the che operon was mapped by primer extension analysis as well as by the construction of promoter reporter plasmids that include several deletion intervals. This analysis indicated that the R. centenum che operon utilizes two promoters; one exhibits a sigma 70-like sequence motif, and the other exhibits a sigma 54-like motif. Expression of the che operon is shown to be relatively constant for swimmer cells which contain a single flagellum and for swarm cells that contain multiple lateral flagella.
Collapse
Affiliation(s)
- Z Y Jiang
- Department of Biology, Indiana University, Bloomington 47405, USA
| | | |
Collapse
|
19
|
Ponnampalam SN, Bauer CE. DNA binding characteristics of CrtJ. A redox-responding repressor of bacteriochlorophyll, carotenoid, and light harvesting-II gene expression in Rhodobacter capsulatus. J Biol Chem 1997; 272:18391-6. [PMID: 9218481 DOI: 10.1074/jbc.272.29.18391] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Previous genetic analysis indicated that the photosynthesis gene cluster from Rhodobacter capsulatus coded for the transcription factor, CrtJ, that is responsible for aerobic repression of bacteriochlorophyll, carotenoid, and light harvesting-II gene expression. In this study, we have heterologously overexpressed and purified CrtJ to homogeneity and shown by gel mobility shift assays that CrtJ is biologically active. DNase I footprint analysis confirms molecular genetic studies by showing that CrtJ binds to conserved palindromic sequences that overlap the -10 and -35 promoter regions of the bchC operon. Graphs of the percentage of DNA bound versus protein concentration show sigmoidal curves, which is highly indicative of cooperative binding of CrtJ to the two palindromic sites. A binding constant for interaction of CrtJ with the palindrome that spans the -10 region was calculated to be 4.8 x 10(-9) M, whereas affinity for the palindrome that spans the -35 region was found to be 2.9 x 10(-9) M. Binding of CrtJ to the bchC promoter region was also found to be redox-sensitive, with CrtJ exhibiting a 4.5-fold higher binding affinity under oxidizing versus reducing conditions.
Collapse
Affiliation(s)
- S N Ponnampalam
- Department of Biology, Indiana University, Bloomington, Indiana 47405, USA
| | | |
Collapse
|
20
|
Hagemann GE, Katsiou E, Forkl H, Steindorf AC, Tadros MH. Gene cloning and regulation of gene expression of the puc operon from Rhodovulum sulfidophilum. BIOCHIMICA ET BIOPHYSICA ACTA 1997; 1351:341-58. [PMID: 9130598 DOI: 10.1016/s0167-4781(96)00228-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Rhodovulum (Rhv.) sulfidophilum, unlike other nonsulfur purple bacteria, is able to synthesize the peripheral antenna complex even under fully aerobic conditions in the dark. We have obtained strong evidence that Rhv. sulfidophilum encodes only one copy of the puc operon, comprising pucB, pucA and pucC. pucB and pucA encode the beta- and alpha-polypeptides. The third ORF (pucC), downstream of pucA, has a strong homology to pucC of Rhodobacter (Rb.) capsulatus. Deletion mutation analysis indicated that the requirement for the pucC gene product for LH II expression was less strict than in Rb. capsulatus. Comparison of the deduced alpha and beta polypeptide sequences with the directly determined primary structure revealed a C-terminal processing of the alpha-subunit. Primer extension analysis showed that the pucBAC is transcribed from a sigma70-type promoter 130 bases upstream of the translational start of pucB. Transcriptional expression of the pucBAC operon in Rhv. sulfidophilum is higher, the lower the light intensity is, and is not reduced to a ground-level by the presence of oxygen. Based on lacZ fusions the relative promoter activities were, for dark aerobic:dark semiaerobic:low light anaerobic:medium light anaerobic:high light anaerobic, 5.5:7.0:2.0:1.0:0.78. Still unidentified cis-regulatory elements or binding sites of trans-regulatory elements are apparently localized in two distinct upstream regions. Furthermore, comparison of the promoter region of the Rhv. sulfidophilum pucBAC with the promoter regions of puc operons in related species showed distinct differences in the regulatory elements. The significance of these results with respect to the regulation of transcription and the oxygen-independent synthesis of LH II from Rhv. sulfidophilum is discussed.
Collapse
MESH Headings
- Amino Acid Sequence
- Bacteria/genetics
- Bacteria/growth & development
- Bacteria/metabolism
- Bacterial Proteins
- Base Sequence
- Chromosome Mapping
- Cloning, Molecular
- Gene Deletion
- Gene Expression Regulation, Bacterial
- Light-Harvesting Protein Complexes
- Molecular Sequence Data
- Mutation
- Open Reading Frames
- Operon/genetics
- Photosynthetic Reaction Center Complex Proteins/genetics
- Photosystem II Protein Complex
- Promoter Regions, Genetic
- Protein Biosynthesis
- RNA, Bacterial/genetics
- RNA, Bacterial/metabolism
- RNA, Messenger/metabolism
- Recombinant Fusion Proteins/genetics
- Recombinant Fusion Proteins/metabolism
- Sequence Analysis, DNA
- Sequence Homology, Amino Acid
- Sequence Homology, Nucleic Acid
- Transcription, Genetic
- beta-Galactosidase/genetics
- beta-Galactosidase/metabolism
Collapse
Affiliation(s)
- G E Hagemann
- Institute for Biology II/Microbiology, University of Freiburg, Germany
| | | | | | | | | |
Collapse
|
21
|
Affiliation(s)
- C E Bauer
- Department of Biology, Indiana University, Bloomington, 47405, USA
| | | |
Collapse
|
22
|
Gomelsky M, Kaplan S. The Rhodobacter sphaeroides 2.4.1 rho gene: expression and genetic analysis of structure and function. J Bacteriol 1996; 178:1946-54. [PMID: 8606169 PMCID: PMC177890 DOI: 10.1128/jb.178.7.1946-1954.1996] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The gene which encodes transcription termination factor Rho from Rhodobacter sphaeroides 2.4.1, the gram-negative facultative photosynthetic bacterium, has been cloned and sequenced. The deduced protein shows a high level of sequence similarity to other bacterial Rho factors, especially those from proteobacteria. However, several amino acid substitutions in the conserved ATP-binding site have been identified. When expressed in Escherichia coli, the R. sphaeroides rho gene relieves Rho-dependent polarity of the trp operon, indicating interference with the transcription termination machinery of E. coli. A truncated version of R. sphaeroides Rho (Rho') is toxic to a bacterium related to R. sphaeroides, Paracoccus denitrificans, and is lethal to R. sphaeroides. We suggest that toxicity is due to the ability of Rho' to form inactive heteromers with the chromosomally encoded intact Rho. We localized a minimal amino acid sequence within Rho which appears to be critical for its toxic effect and which we believe may be involved in protein-protein interactions. This region was previously reported to be highly conserved and unique among various Rho proteins. The lethality of rho' in R. sphaeroides together with our inability to obtain a null mutation in rho suggests that Rho-dependent transcription termination is essential in R. sphaeroides. This is analogous to what is observed for gram-negative E. coli and contrasts with what is observed for gram-positive Bacillus subtilis. The genetic region surrounding the R. sphaeroides rho gene has been determined and found to be different compared with those of other bacterial species. rho is preceded by orf1, which encodes a putative integral membrane protein possibly involved in cytochrome formation or functioning. The gene downstream of rho is homologous to thdF, whose product is involved in thiophene and furan oxidation.
Collapse
Affiliation(s)
- M Gomelsky
- Department of Microbiology and Molecular Genetics, The University of Texas Medical School at Houston, Texas 77030, USA
| | | |
Collapse
|
23
|
Forkl H, Drews G, Tadros MH. Promoter analysis of the catalase-peroxidase gene (cpeA) from Rhodobacter capsulatus. FEMS Microbiol Lett 1996; 137:169-74. [PMID: 8998981 DOI: 10.1111/j.1574-6968.1996.tb08101.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The expression of the Rhodobacter capsulatus catalase-peroxidase (cpeA) was studied by in-frame fusions of the upstream region of the cpeA gene to a promoter-less lacZ gene. The transcription of the cpeA gene is about 20-50-fold higher under aerobic-dark than under anaerobic-light conditions. The promoter was localized within a 69-bp upstream DNA region. The transcription start site, determined by primer extension, is 28 bases upstream from the initiation codon, confirming the postulated promoter localized by deletion analysis. Deletion of the part of the upstream region specifically responsible for oxygen regulation resulted in constitutive expression of the cpeA gene.
Collapse
Affiliation(s)
- H Forkl
- Institut für Biologie 2/Mikrobiologie, Albert-Ludwigs-Universität, Freiburg, Germany
| | | | | |
Collapse
|
24
|
Pasternak C, Assemat K, Breton AM, Clement-Metral JD, Klug G. Expression of the thioredoxin gene (trxA) in Rhodobacter sphaeroides Y is regulated by oxygen. MOLECULAR & GENERAL GENETICS : MGG 1996; 250:189-96. [PMID: 8628218 DOI: 10.1007/bf02174178] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The structural gene (trxA) coding for thioredoxin in the photosynthetic bacterium Rhodobacter sphaeroides has been cloned and sequenced previously. In the present study, the role of oxygen in trxA expression in R. sphaeroides Y was investigated using mRNA analyses and plasmid-borne trxA'-lacZ+ translational and transcriptional fusions. Northern analysis revealed a trxA-specific transcript of approximately 420-460 nucleotides, indicating that trxA is transcribed as a single gene. By studying the beta-galactosidase activity in strains harboring various phi(trxA'-lacZ+) fusion constructs, the promoter region of the trxA gene was localized within a 64-bp region located 97 nucleotides upstream of the trxA initiator codon. A single trxA transcription initiation site was mapped by primer extension, 27 bp upstream of the trxA gene. Based on these results and the DNA sequence analysis, we propose that a sigma70 consensus sequence serves as a trxA promoter. Results from oxygen shift experiments, as deduced from both mRNA analysis and fusions of the trxA promoter region to lacZ indicate that transcription of the R. sphaeroides trxA gene is regulated by high oxygen tension. DNA sequences involved in this oxygen regulation were also localized in the 64-bp region containing the trxA promoter. Based on our findings the hypothetical biological function of thioredoxin from R. sphaeroides is discussed.
Collapse
Affiliation(s)
- C Pasternak
- Laboratoire de Technologie Enzymatique, Université de Technologie de Compiègne, France
| | | | | | | | | |
Collapse
|
25
|
Fidai S, Dahl JA, Richards WR. Effect of the PufQ protein on early steps in the pathway of bacteriochlorophyll biosynthesis in Rhodobacter capsulatus. FEBS Lett 1995; 372:264-8. [PMID: 7556681 DOI: 10.1016/0014-5793(95)00995-l] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The addition in trans of the pufQ gene to a strain of Rhodobacter capsulatus from which the entire puf operon had been deleted, increased its ability to synthesize coproporphyrinogen from both delta-aminolevulinic acid and porphobilinogen. Studies at the enzyme level indicated that the conversion of porphobilinogen to uroporphyrinogen III had about a 2-fold higher level of activity in the anaerobically-grown pufQ-containing strain. This increase in activity over the puf-deletion strain appeared to occur during transitions from aerobic to semiaerobic growth conditions. These results indicated that the PufQ protein may exert a stimulatory effect quite early in the pathway of bacteriochlorophyll biosynthesis.
Collapse
Affiliation(s)
- S Fidai
- Department of Chemistry, Simon Fraser University, Burnaby, B.C., Canada
| | | | | |
Collapse
|
26
|
Lee JK, Kaplan S. Transcriptional Regulation of puc Operon Expression in Rhodobacter sphaeroides. J Biol Chem 1995. [DOI: 10.1074/jbc.270.35.20453] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
|
27
|
Pollich M, Klug G. Identification and sequence analysis of genes involved in late steps in cobalamin (vitamin B12) synthesis in Rhodobacter capsulatus. J Bacteriol 1995; 177:4481-7. [PMID: 7635831 PMCID: PMC177200 DOI: 10.1128/jb.177.15.4481-4487.1995] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
A 6.4-kb region of a 6.8-kb BamHI fragment carrying Rhodobacter capsulatus genes involved in late steps of cobalamin synthesis has been sequenced. The nucleotide sequence and genetic analysis revealed that this fragment contains eight genes arranged in at least three operons. Five of these eight genes show homology to genes involved in the cobalamin synthesis of Pseudomonas denitrificans and Salmonella typhimurium. The arrangement of these homologous genes differs considerably in the three genera. Upstream of five overlapping genes (named bluFEDCB), a promoter activity could be detected by using lacZ fusions. This promoter shows no regulation by oxygen, vitamin B12 (cobalamin), or cobinamide. Disruption of the bluE gene by a Tn5 insertion (strain AH2) results in reduced expression of the puf and puc operons, which encode pigment-binding proteins of the photosynthetic apparatus. The mutant strain AH2 can be corrected to a wild-type-like phenotype by addition of vitamin B12 or cobinamide dicyanide. Disruption of the bluB gene by an interposon (strain BB1) also disturbs the formation of the photosynthetic apparatus. The mutation of strain BB1 can be corrected by vitamin B12 but not by cobinamide. We propose that a lack of cobalamin results in deregulation and a decreased formation of the photosynthetic apparatus.
Collapse
Affiliation(s)
- M Pollich
- Institut für Mikro- und Molekularbiologie, Giessen, Germany
| | | |
Collapse
|
28
|
Ponnampalam SN, Buggy JJ, Bauer CE. Characterization of an aerobic repressor that coordinately regulates bacteriochlorophyll, carotenoid, and light harvesting-II expression in Rhodobacter capsulatus. J Bacteriol 1995; 177:2990-7. [PMID: 7768793 PMCID: PMC176984 DOI: 10.1128/jb.177.11.2990-2997.1995] [Citation(s) in RCA: 79] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
For most species of purple photosynthetic bacteria, the presence of molecular oxygen represses synthesis of carotenoids and bacteriochlorophyll. In this study we characterize a strain of Rhodobacter capsulatus, DB469, which contains a genomic disruption of an open reading frame in the photosynthesis gene cluster termed ORF469. Characterization of the steady-state level of bacteriochlorophyll synthesis demonstrates that disruption of ORF469 results in a 2.5-fold increase in aerobic synthesis of bacteriochlorophyll over that observed with the parent strain. Utilizing reporter plasmids that contain transcriptional fusions of lacZ to various carotenoid and bacteriochlorophyll biosynthesis genes, we also demonstrate that disruption of ORF469 leads to an approximate twofold increase in bacteriochlorophyll and carotenoid gene expression under anaerobic growth conditions. Similar analysis with reporter plasmids that contain translational fusions of lacZ to the puf, puh, and puc operons demonstrates that disruption of ORF469 leads to elevated levels of aerobic transcription of light harvesting-II genes (puc), without affecting light harvesting-I or reaction center gene expression (puf and puh, respectively). Gel mobility analysis demonstrates that DB469 cells lack a DNA-binding protein that interacts with a palindromic sequence in the bchC promoter region. The results of this study indicate that ORF469 codes for a DNA-binding protein that acts as an aerobic repressor of promoters for bacteriochlorophyll, carotenoid, and light harvesting-II gene expression.
Collapse
Affiliation(s)
- S N Ponnampalam
- Department of Chemistry, Indiana University, Bloomington 47405, USA
| | | | | |
Collapse
|
29
|
Ma D, Cook DN, Alberti M, Pon NG, Nikaido H, Hearst JE. Genes acrA and acrB encode a stress-induced efflux system of Escherichia coli. Mol Microbiol 1995; 16:45-55. [PMID: 7651136 DOI: 10.1111/j.1365-2958.1995.tb02390.x] [Citation(s) in RCA: 450] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Defined mutations of acrA or acrB (formerly acrE) genes increased the susceptibility of Escherichia coli to a range of small inhibitor molecules. Deletion of acrAB increased susceptibility to cephalothin and cephaloridine, but the permeability of these beta-lactams across the outer membrane was not increased. This finding is inconsistent with the earlier hypothesis that acrAB mutations increase drug susceptibility by increasing the permeability of the outer membrane, and supports our model that acrAB codes for a multi-drug efflux pump. The natural environment of an enteric bacterium such as E. coli is enriched in bile salts and fatty acids. An acrAB deletion mutant was found to be hypersusceptible to bile salts and to decanoate. In addition, acrAB expression was elevated by growth in 5 mM decanoate. These results suggest that one major physiological function of AcrAB is to protect E. coli against these and other hydrophobic inhibitors. Transcription of acrAB is increased by other stress conditions including 4% ethanol, 0.5 M NaCl, and stationary phase in Luria-Bertani medium. Finally, acrAB expression was shown to be increased in mar (multiple-antibiotic-resistant) mutants.
Collapse
Affiliation(s)
- D Ma
- Department of Chemistry, University of California, Berkeley 94720, USA
| | | | | | | | | | | |
Collapse
|
30
|
Gomelsky M, Kaplan S. Genetic evidence that PpsR from Rhodobacter sphaeroides 2.4.1 functions as a repressor of puc and bchF expression. J Bacteriol 1995; 177:1634-7. [PMID: 7883723 PMCID: PMC176785 DOI: 10.1128/jb.177.6.1634-1637.1995] [Citation(s) in RCA: 83] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The ppsR gene (R. J. Penfold and J. M. Pemberton, J. Bacteriol. 176:2869-2876, 1994) from Rhodobacter sphaeroides 2.4.1 functions as a transcriptional repressor of puc and bchF expression. The carboxy terminus of PpsR, containing the putative DNA-binding domain, by itself possesses repressor activity. Intact palindromes having the motif TGT-N12-ACA are required for PpsR activity.
Collapse
Affiliation(s)
- M Gomelsky
- Department of Microbiology and Molecular Genetics, University of Texas Health Science Center Medical School, Houston 77030
| | | |
Collapse
|
31
|
Watanabe Y, Feick RG, Shiozawa JA. Cloning and sequencing of the genes encoding the light-harvesting B806-866 polypeptides and initial studies on the transcriptional organization of puf2B, puf2A and puf2C in Chloroflexus aurantiacus. Arch Microbiol 1995; 163:124-30. [PMID: 7535995 DOI: 10.1007/bf00381786] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The genes encoding the alpha- and beta-polypeptide subunits of the B806-866 membrane-bound light-harvesting complex of Chloroflexus aurantiacus have been cloned and the nucleotide sequences determined. The gene puf2A, which encodes the B806-866 alpha-polypeptide, began 28 bases downstream of the stop codon of puf2B, which encodes the B806-866 beta gene. The gene-encoding cytochrome c-554, puf2C, was found about 250 bp downstream of puf2A. puf2A encoded a 13 amino acid extension at the C-terminus of the B806-866 alpha-polypeptide that was not present in the mature protein. These genes, unlike those of purple nonsulfur bacteria, did not form a contiguous operon with puf1L or puf1M, the genes encoding the L and M subunits of the photochemical reaction center. The occurrence of the two latter genes and of puf2B and puf2A in two separate operons has not been observed in purple bacteria. Under photoheterotrophic growth conditions, puf2B and puf2A were encoded on an abundant mRNA that was 0.5 kb long. Two monocistronic transcripts for puf2C were observed that had different 5'-ends. One transcript encoding all three genes was also detected. Nucleotide sequences very similar to the consensus promoter sequence of the Escherichia coli RNA polymerase sigma 70 subunit were found seven and eight bases upstream of the 5'-end of mRNA encoding puf2B and for one of the monocistronic mRNA encoding puf2C, respectively.
Collapse
Affiliation(s)
- Y Watanabe
- Max-Planck-Institut für Biochemie, Martinsried, Germany
| | | | | |
Collapse
|
32
|
Fidai S, Hinchigeri SB, Borgford TJ, Richards WR. Identification of the PufQ protein in membranes of Rhodobacter capsulatus. J Bacteriol 1994; 176:7244-51. [PMID: 7961495 PMCID: PMC197112 DOI: 10.1128/jb.176.23.7244-7251.1994] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The PufQ protein has been detected in vivo for the first time by Western blot (immunoblot) analyses of the chromatophore membranes of Rhodobacter capsulatus. The PufQ protein was not visible in Western blots of membranes of a mutant (delta RC6) lacking the puf operon but appeared in membranes of the same mutant to which the pufQ gene had been added in trans. It was also detected in elevated amounts in a mutant (CB1200) defective in two bch genes and unable, therefore, to make bacteriochlorophyll. The extremely hydrophobic nature of the PufQ protein was also apparent in these studies since it was not extracted from chromatophores by 3% (wt/vol) n-octyl-beta-D-glucopyranoside, a procedure which solubilized the reaction center and light-harvesting complexes. During adaptation of R. capsulatus from aerobic to semiaerobic growth conditions (during which time the synthesis of bacteriochlorophyll was induced), the PufQ protein was observed to increase to the level of detection in the developing chromatophore fraction approximately 3 h after the start of the adaptation. The enzyme, S-adenosyl-L-methionine:magnesium protoporphyrin methyltransferase, also increased in amount in the developing chromatophore fraction but was present in a cell membrane fraction at the start of the adaptation as well.
Collapse
Affiliation(s)
- S Fidai
- Department of Chemistry, Simon Fraser University, Burnaby, British Columbia, Canada
| | | | | | | |
Collapse
|
33
|
Penfold RJ, Pemberton JM. Sequencing, chromosomal inactivation, and functional expression in Escherichia coli of ppsR, a gene which represses carotenoid and bacteriochlorophyll synthesis in Rhodobacter sphaeroides. J Bacteriol 1994; 176:2869-76. [PMID: 8188588 PMCID: PMC205441 DOI: 10.1128/jb.176.10.2869-2876.1994] [Citation(s) in RCA: 100] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Sequencing of a DNA fragment that causes trans suppression of bacteriochlorophyll and carotenoid levels in Rhodobacter sphaeroides revealed two genes: orf-192 and ppsR. The ppsR gene alone is sufficient for photopigment suppression. Inactivation of the R. sphaeroides chromosomal copy of ppsR results in overproduction of both bacteriochlorophyll and carotenoid pigments. The deduced 464-amino-acid protein product of ppsR is homologous to the CrtJ protein of Rhodobacter capsulatus and contains a helix-turn-helix domain that is found in various DNA-binding proteins. Removal of the helix-turn-helix domain renders PpsR nonfunctional. The promoter of ppsR is located within the coding region of the upstream orf-192 gene. When this promoter is replaced by a lacZ promoter, ppsR is expressed in Escherichia coli. An R. sphaeroides DNA fragment carrying crtD', -E, and -F and bchC, -X, -Y, and -Z' exhibited putative promoter activity in E. coli. This putative promoter activity could be suppressed by PpsR in both E. coli and R. sphaeroides. These results suggest that PpsR is a transcriptional repressor. It could potentially act by binding to a putative regulatory palindrome found in the 5' flanking regions of a number of R. sphaeroides and R. capsulatus photosynthesis genes.
Collapse
Affiliation(s)
- R J Penfold
- Microbiology Department, University of Queensland, St. Lucia, Brisbane, Australia
| | | |
Collapse
|
34
|
Buggy JJ, Sganga MW, Bauer CE. Nucleotide sequence and characterization of the Rhodobacter capsulatus hvrB gene: HvrB is an activator of S-adenosyl-L-homocysteine hydrolase expression and is a member of the LysR family. J Bacteriol 1994; 176:61-9. [PMID: 8282711 PMCID: PMC205014 DOI: 10.1128/jb.176.1.61-69.1994] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Here we present the nucleotide sequence and characterization of two genes, hvrB and orf5, that are located in the regulatory gene cluster from Rhodobacter capsulatus. The hvrB gene, which encodes a protein with a predicted molecular mass of 32 kDa, is shown to be highly homologous to genes encoding members of the LysR family of bacterial transcriptional regulators. A chromosomal disruption of hvrB is shown to result in the failure to regulate expression from the nearby ahcY and orf5 genes in response to alterations in light intensity. We show by primer extension mapping that the 5' end of ahcY-specific mRNA defines a promoter region exhibiting sequence similarity to known R. capsulatus promoter elements. Our mutational analysis further demonstrates that hvrB autoregulates its own expression in vivo.
Collapse
Affiliation(s)
- J J Buggy
- Department of Biology, Indiana University, Bloomington 47405
| | | | | |
Collapse
|
35
|
Karls RK, Jin DJ, Donohue TJ. Transcription properties of RNA polymerase holoenzymes isolated from the purple nonsulfur bacterium Rhodobacter sphaeroides. J Bacteriol 1993; 175:7629-38. [PMID: 8244932 PMCID: PMC206919 DOI: 10.1128/jb.175.23.7629-7638.1993] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
We have been characterizing RNA polymerase holoenzymes from Rhodobacter sphaeroides. RNA polymerase purified from R. sphaeroides transcribed from promoters recognized by Escherichia coli E sigma 32 or E sigma 70 holoenzyme. Antisera to E. coli sigma 32 or sigma 70 indicated that related polypeptides of approximately 37 kDa (sigma 37) and 93 kDa (sigma 93), respectively, are present in this preparation. Transcription of sigma 32-dependent promoters was observed in a further fractionated R. sphaeroides holoenzyme containing the sigma 37 polypeptide, while a preparation enriched in sigma 93 transcribed sigma 70-dependent promoters. To demonstrate further that the sigma 93 polypeptide functions like E. coli sigma 70, we obtained an R. sphaeroides E sigma 93 holoenzyme capable of transcription from sigma 70-dependent promoters by combining sigma 93 with (i) an E sigma 37 fraction with diminished sigma 93 polypeptide content or (ii) E. coli core RNA polymerase. The generation of analogous DNase I footprints on the lacUV5 promoter by R. sphaeroides E sigma 93 and by E. coli E sigma 70 suggests that the overall structures of these two holoenzymes are similar. However, some differences in promoter specificity between R. sphaeroides E sigma 93 and E. coli E sigma 70 exist because transcription of an R. sphaeroides rRNA promoter was detected only with E sigma 93.
Collapse
Affiliation(s)
- R K Karls
- Department of Bacteriology, University of Wisconsin-Madison 53706
| | | | | |
Collapse
|
36
|
Varga A, Kaplan S. Synthesis and stability of reaction center polypeptides and implications for reaction center assembly in Rhodobacter sphaeroides. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(19)36590-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
|
37
|
Burke DH, Alberti M, Hearst JE. bchFNBH bacteriochlorophyll synthesis genes of Rhodobacter capsulatus and identification of the third subunit of light-independent protochlorophyllide reductase in bacteria and plants. J Bacteriol 1993; 175:2414-22. [PMID: 8385667 PMCID: PMC204531 DOI: 10.1128/jb.175.8.2414-2422.1993] [Citation(s) in RCA: 59] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
We present the nucleotide and deduced amino acid sequences of four contiguous bacteriochlorophyll synthesis genes from Rhodobacter capsulatus. Three of these genes code for enzymes which catalyze reactions common to the chlorophyll synthesis pathway and therefore are likely to be found in plants and cyanobacteria as well. The pigments accumulated in strains with physically mapped transposon insertion mutations are analyzed by absorbance and fluorescence spectroscopy, allowing us to assign the genes as bchF, bchN, bchB, and bchH, in that order. bchF encodes a bacteriochlorophyll alpha-specific enzyme that adds water across the 2-vinyl group. The other three genes are required for portions of the pathway that are shared with chlorophyll synthesis, and they were expected to be common to both pathways. bchN and bchB are required for protochlorophyllide reduction in the dark (along with bchL), a reaction that has been observed in all major groups of photosynthetic organisms except angiosperms, where only the light-dependent reaction has been clearly established. The purple bacterial and plant enzymes show 35% identity between the amino acids coded by bchN and chlN (gidA) and 49% identity between the amino acids coded by bchL and chlL (frxC). Furthermore, bchB is 33% identical to ORF513 from the Marchantia polymorpha chloroplast. We present arguments in favor of the probable role of ORF513 (chlB) in protochlorophyllide reduction in the dark. The further similarities of all three subunits of protochlorophyllide reductase and the three subunits of chlorin reductase in bacteriochlorophyll synthesis suggest that the two reductase systems are derived from a common ancestor.
Collapse
Affiliation(s)
- D H Burke
- Department of Chemistry, University of California, Berkeley
| | | | | |
Collapse
|