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Howarth RE, Pattillo CM, Griffitts JS, Calvopina-Chavez DG. Three genes controlling streptomycin susceptibility in Agrobacterium fabrum. J Bacteriol 2023; 205:e0016523. [PMID: 37695858 PMCID: PMC10521367 DOI: 10.1128/jb.00165-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Accepted: 08/05/2023] [Indexed: 09/13/2023] Open
Abstract
Streptomycin (Sm) is a commonly used antibiotic for its efficacy against diverse bacteria. The plant pathogen Agrobacterium fabrum is a model for studying pathogenesis and interkingdom gene transfer. Streptomycin-resistant variants of A. fabrum are commonly employed in genetic analyses, yet mechanisms of resistance and susceptibility to streptomycin in this organism have not previously been investigated. We observe that resistance to a high concentration of streptomycin arises at high frequency in A. fabrum, and we attribute this trait to the presence of a chromosomal gene (strB) encoding a putative aminoglycoside phosphotransferase. We show how strB, along with rpsL (encoding ribosomal protein S12) and rsmG (encoding a 16S rRNA methyltransferase), modulates streptomycin sensitivity in A. fabrum. IMPORTANCE The plant pathogen Agrobacterium fabrum is a widely used model bacterium for studying biofilms, bacterial motility, pathogenesis, and gene transfer from bacteria to plants. Streptomycin (Sm) is an aminoglycoside antibiotic known for its broad efficacy against gram-negative bacteria. A. fabrum exhibits endogenous resistance to somewhat high levels of streptomycin, but the mechanism underlying this resistance has not been elucidated. Here, we demonstrate that this resistance is caused by a chromosomally encoded streptomycin-inactivating enzyme, StrB, that has not been previously characterized in A. fabrum. Furthermore, we show how the genes rsmG, rpsL, and strB jointly modulate streptomycin susceptibility in A. fabrum.
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Affiliation(s)
- Robyn E. Howarth
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, Utah, USA
| | - Curtis M. Pattillo
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, Utah, USA
| | - Joel S. Griffitts
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, Utah, USA
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Abedeera SM, Hawkins CM, Abeysirigunawardena SC. RsmG forms stable complexes with premature small subunit rRNA during bacterial ribosome biogenesis. RSC Adv 2020; 10:22361-22369. [PMID: 35514586 PMCID: PMC9054591 DOI: 10.1039/d0ra02732d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Accepted: 06/01/2020] [Indexed: 12/22/2022] Open
Abstract
The ribosome is the ribonucleoprotein machine that carries out protein biosynthesis in all forms of life. Perfect synchronization between ribosomal RNA (rRNA) transcription, folding, post-transcriptional modification, maturation, and assembly of r-proteins is essential for the rapid formation of structurally and functionally accurate ribosomes. Many RNA nucleotide modification enzymes may function as assembly factors that oversee the accuracy of ribosome assembly. The protein RsmG is a methyltransferase enzyme that is responsible for N7 methylation in G527 of 16S rRNA. Here we illustrate the ability of RsmG to bind various premature small subunit ribosomal RNAs with contrasting affinities. Protein RsmG binds with approximately 15-times higher affinity to premature 16S rRNA with the full leader sequence compared to that of mature 16S rRNA. Various r-proteins which bind to the 5′-domain influence RsmG binding. The observed binding cooperativity between RsmG and r-proteins is sensitive to the maturation status of premature small subunit rRNA. However, neither the maturation of 16S rRNA nor the presence of various r-proteins significantly influence the methylation activity of RsmG. The capability of RsmG to bind to premature small subunit rRNA and alter its binding preference to various RNA–protein complexes based on the maturation of rRNA indicates its ability to influence ribosome assembly. RsmG is the methyltransferase responsible for the N7 methylation of G527 of 16S rRNA. Here we show that RsmG binds preferably to premature bacterial small subunit rRNA. The presence of ribosomal proteins also influences the stability of RsmG–rRNA complexes.![]()
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Affiliation(s)
- Sudeshi M Abedeera
- Department of Chemistry and Biochemistry, Kent State University Kent Ohio 44242 USA
| | - Caitlin M Hawkins
- Department of Chemistry and Biochemistry, Kent State University Kent Ohio 44242 USA
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Dasgupta R, Ganguly HK, Modugula EK, Basu G. Type VIa β-turn-fused helix N-termini: A novel helix N-cap motif containing cis proline. Biopolymers 2016; 108. [PMID: 27428516 DOI: 10.1002/bip.22919] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Revised: 07/07/2016] [Accepted: 07/14/2016] [Indexed: 11/05/2022]
Abstract
Helix N-capping motifs often form hydrogen bonds with terminal amide groups which otherwise would be free. Also, without an amide hydrogen, proline (trans) is over-represented at helix N-termini (N1 position) because this naturally removes the need to hydrogen bond one terminal amide. However, the preference of cisPro, vis-à-vis helix N-termini, is not known. We show that cisPro (αR or PPII ) often appears at the N-cap position (N0) of helices. The N-cap cisPro(αR ) is associated with a six-residue sequence motif - X(-2) -X(-1) -cisPro-X(1) -X(2) -X(3) - with preference for Glu/Gln at X(-1) , Phe/Tyr/Trp at X(1) and Ser/Thr at X(3) . The motif, formed by the fusion of a helix and a type VIa β-turn, contains a hydrogen bond between the side chain of X(-1) and the side chain/backbone of X(3) , a α-helical hydrogen bond between X(-2) and X(2) and stacking interaction between cisPro and an aromatic residue at X(1) . NMR experiments on peptides containing the motif and its variants showed that local interactions associated with the motif, as found in folded proteins, were not enough to significantly tilt the cis/trans equilibrium towards cisPro. This suggests that some other evolutionary pressure must select the cisPro motif (over transPro) at helix N-termini. Database analysis showed that >C = O of the pre-cisPro(αR ) residue at the helix N-cap, directed opposite to the N→C helical axis, participates in long-range interactions. We hypothesize that the cisPro(αR ) motif is preferred at helix N-termini because it allows the helix to participate in long-range interactions that may be structurally and functionally important.
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Affiliation(s)
- Rubin Dasgupta
- Department of Biophysics, Bose Institute, P-1/12 CIT Scheme VIIM, Kolkata, 700054, India
| | - Himal K Ganguly
- Department of Biophysics, Bose Institute, P-1/12 CIT Scheme VIIM, Kolkata, 700054, India
| | - E K Modugula
- Department of Biophysics, Bose Institute, P-1/12 CIT Scheme VIIM, Kolkata, 700054, India
| | - Gautam Basu
- Department of Biophysics, Bose Institute, P-1/12 CIT Scheme VIIM, Kolkata, 700054, India
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Shippy DC, Fadl AA. RNA modification enzymes encoded by the gid operon: Implications in biology and virulence of bacteria. Microb Pathog 2015; 89:100-7. [PMID: 26427881 DOI: 10.1016/j.micpath.2015.09.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Accepted: 09/23/2015] [Indexed: 01/10/2023]
Abstract
Ribonucleic acid (RNA) molecules consist of numerous chemically modified nucleosides that are highly conserved in eukarya, archeae, and bacteria, while others are unique to each domain of life. In bacteria, hundreds of RNA modification enzymes have been identified and implicated in biological pathways associated with many cell processes. The glucose-inhibited division (gid) operon encodes genes for two RNA modification enzymes named GidA and GidB. Studies have shown GidA is essential for the proper biosynthesis of 5-methylaminomethyl-2-thiouridine (mnm(5)s(2)U) of bacterial transfer RNA (tRNA) with GidB responsible for the methylation of the 16S ribosomal RNA (rRNA). Furthermore, deletion of gidA and gidB has shown to alter numerous bacterial properties like virulence, stress response, morphology, growth, antibiotic susceptibility, and others. In this review, we discuss the present knowledge of the RNA modification enzymes GidA and GidB, and their potential role in the biology and virulence of bacteria.
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Affiliation(s)
- Daniel C Shippy
- Department of Animal Sciences, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Amin A Fadl
- Department of Animal Sciences, University of Wisconsin-Madison, Madison, WI 53706, USA.
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Mosquera-Rendón J, Cárdenas-Brito S, Pineda JD, Corredor M, Benítez-Páez A. Evolutionary and sequence-based relationships in bacterial AdoMet-dependent non-coding RNA methyltransferases. BMC Res Notes 2014; 7:440. [PMID: 25012753 PMCID: PMC4119055 DOI: 10.1186/1756-0500-7-440] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Accepted: 07/02/2014] [Indexed: 12/12/2022] Open
Abstract
Background RNA post-transcriptional modification is an exciting field of research that has evidenced this editing process as a sophisticated epigenetic mechanism to fine tune the ribosome function and to control gene expression. Although tRNA modifications seem to be more relevant for the ribosome function and cell physiology as a whole, some rRNA modifications have also been seen to play pivotal roles, essentially those located in central ribosome regions. RNA methylation at nucleobases and ribose moieties of nucleotides appear to frequently modulate its chemistry and structure. RNA methyltransferases comprise a superfamily of highly specialized enzymes that accomplish a wide variety of modifications. These enzymes exhibit a poor degree of sequence similarity in spite of using a common reaction cofactor and modifying the same substrate type. Results Relationships and lineages of RNA methyltransferases have been extensively discussed, but no consensus has been reached. To shed light on this topic, we performed amino acid and codon-based sequence analyses to determine phylogenetic relationships and molecular evolution. We found that most Class I RNA MTases are evolutionarily related to protein and cofactor/vitamin biosynthesis methyltransferases. Additionally, we found that at least nine lineages explain the diversity of RNA MTases. We evidenced that RNA methyltransferases have high content of polar and positively charged amino acid, which coincides with the electrochemistry of their substrates. Conclusions After studying almost 12,000 bacterial genomes and 2,000 patho-pangenomes, we revealed that molecular evolution of Class I methyltransferases matches the different rates of synonymous and non-synonymous substitutions along the coding region. Consequently, evolution on Class I methyltransferases selects against amino acid changes affecting the structure conformation.
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Affiliation(s)
| | | | | | | | - Alfonso Benítez-Páez
- Bioinformatics Analysis Group - GABi, Centro de Investigación y Desarrollo en Biotecnología - CIDBIO, 111221 Bogotá, D,C, Colombia.
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Structural analysis of base substitutions in Thermus thermophilus 16S rRNA conferring streptomycin resistance. Antimicrob Agents Chemother 2014; 58:4308-17. [PMID: 24820088 DOI: 10.1128/aac.02857-14] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Streptomycin is a bactericidal antibiotic that induces translational errors. It binds to the 30S ribosomal subunit, interacting with ribosomal protein S12 and with 16S rRNA through contacts with the phosphodiester backbone. To explore the structural basis for streptomycin resistance, we determined the X-ray crystal structures of 30S ribosomal subunits from six streptomycin-resistant mutants of Thermus thermophilus both in the apo form and in complex with streptomycin. Base substitutions at highly conserved residues in the central pseudoknot of 16S rRNA produce novel hydrogen-bonding and base-stacking interactions. These rearrangements in secondary structure produce only minor adjustments in the three-dimensional fold of the pseudoknot. These results illustrate how antibiotic resistance can occur as a result of small changes in binding site conformation.
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Culver GM, Rife JP. Involvement of Ribosome Biogenesis in Antibiotic Function, Acquired Resistance, and Future Opportunities in Drug Discovery. Antibiotics (Basel) 2013. [DOI: 10.1002/9783527659685.ch15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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Benítez-Páez A, Villarroya M, Armengod ME. Regulation of expression and catalytic activity of Escherichia coli RsmG methyltransferase. RNA (NEW YORK, N.Y.) 2012; 18:795-806. [PMID: 22337945 PMCID: PMC3312566 DOI: 10.1261/rna.029868.111] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2011] [Accepted: 01/05/2012] [Indexed: 05/31/2023]
Abstract
RsmG is an AdoMet-dependent methyltransferase responsible for the synthesis of m(7)G527 in the 530 loop of bacterial 16S rRNA. This loop is universally conserved, plays a key role in ribosomal accuracy, and is a target for streptomycin binding. Loss of the m(7)G527 modification confers low-level streptomycin resistance and may affect ribosomal functioning. Here, we explore the mechanisms controlling RsmG expression and activity, which may somehow respond to the demand set by the amount of rRNA. We confirm that rsmG is the second member in a bicistronic operon and demonstrate that rsmG also has its own promoter, which appears, in actively growing cells, as a control device to offset both the relatively low stability of RsmG and inhibition of the operon promoter. RsmG levels decrease under conditions that down-regulate rRNA synthesis. However, coordination between rRNA and RsmG expression does not seem to occur at the level of transcription initiation. Instead, it might depend on the activity of an inverted repeated region, located between the rsmG promoter and ribosome binding site, which we show to work as a weak transcriptional terminator. To gain insights into the enzymatic mechanism of RsmG, highly conserved residues were mutated and the abilities of the resulting proteins to confer streptomycin resistance, to modify rRNA, and to bind AdoMet were explored. Our data demonstrate for the first time the critical importance of some residues located in the active site of Escherichia coli RsmG for the m(7)G modification process and suggest a role for them in rRNA binding and catalysis.
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Affiliation(s)
- Alfonso Benítez-Páez
- Laboratorio de Genética Molecular, Centro de Investigación Príncipe Felipe, 46012 Valencia, Spain
- Bioinformatic Analysis Group–GABi, Centro de Investigación y Desarrollo en Biotecnología, Bogotá D.C. 111221, Colombia
| | - Magda Villarroya
- Laboratorio de Genética Molecular, Centro de Investigación Príncipe Felipe, 46012 Valencia, Spain
| | - M.-Eugenia Armengod
- Laboratorio de Genética Molecular, Centro de Investigación Príncipe Felipe, 46012 Valencia, Spain
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Mikheil DM, Shippy DC, Eakley NM, Okwumabua OE, Fadl AA. Deletion of gene encoding methyltransferase (gidB) confers high-level antimicrobial resistance in Salmonella. J Antibiot (Tokyo) 2012; 65:185-92. [DOI: 10.1038/ja.2012.5] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Xiao D, Yin C, Zhang Q, Li JH, Gong PT, Li SH, Zhang GC, Gao YJ, Zhang XC. Selection and identification of a new adhesion protein of Cryptosporidium parvum from a cDNA library by ribosome display. Exp Parasitol 2011; 129:183-9. [DOI: 10.1016/j.exppara.2011.06.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2010] [Revised: 06/13/2011] [Accepted: 06/14/2011] [Indexed: 10/18/2022]
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Parveen N, Cornell KA. Methylthioadenosine/S-adenosylhomocysteine nucleosidase, a critical enzyme for bacterial metabolism. Mol Microbiol 2010; 79:7-20. [PMID: 21166890 DOI: 10.1111/j.1365-2958.2010.07455.x] [Citation(s) in RCA: 184] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The importance of methylthioadenosine/S-adenosylhomocysteine (MTA/SAH) nucleosidase in bacteria has started to be appreciated only in the past decade. A comprehensive analysis of its various roles here demonstrates that it is an integral component of the activated methyl cycle, which recycles adenine and methionine through S-adenosylmethionine (SAM)-mediated methylation reactions, and also produces the universal quorum-sensing signal, autoinducer-2 (AI-2). SAM is also essential for synthesis of polyamines, N-acylhomoserine lactone (autoinducer-1), and production of vitamins and other biomolecules formed by SAM radical reactions. MTA, SAH and 5'-deoxyadenosine (5'dADO) are product inhibitors of these reactions, and are substrates of MTA/SAH nucleosidase, underscoring its importance in a wide array of metabolic reactions. Inhibition of this enzyme by certain substrate analogues also limits synthesis of autoinducers and hence causes reduction in biofilm formation and may attenuate virulence. Interestingly, the inhibitors of MTA/SAH nucleosidase are very effective against the Lyme disease causing spirochaete, Borrelia burgdorferi, which uniquely expresses three homologous functional enzymes. These results indicate that inhibition of this enzyme can affect growth of different bacteria by affecting different mechanisms. Therefore, new inhibitors are currently being explored for development of potential novel broad-spectrum antimicrobials.
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Affiliation(s)
- Nikhat Parveen
- Department of Microbiology and Molecular Genetics, University of Medicine and Dentistry of New Jersey, New Jersey Medical School, 225 Warren Street, Newark, NJ 07103-3535, USA.
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