Systematic sequencing of the Bacillus subtilis genome: progress report of the Japanese group

Identification of laboratory-specific variations of Bacillus subtilis strains used in Japan

The strain of Bacillus subtilis 168 used in laboratories in Japan was distributed in the 1990s when the sequencing consortium commenced operations. After 20 years of use of B. subtilis 168 in many laboratories, observations of variations in growth phenotypes have been reported. In this study, to uncover laboratory-specific variations of B. subtilis 168 strains in Japan, we re-sequenced 11 B. subtilis 168 strains from nine laboratories and analyzed how their genomes differed. We found that the 168 strains from different laboratories differed by 1-7 variations. These variations might have been caused by differences in storage conditions in the laboratories or differences among colonies of the original stock. Based on our results, researchers ought to understand the genetic differences among wild-type (parental) strains in different laboratories and the reference strain by re-sequencing analysis, and ought to pay more attention to the management of laboratory strains.

Cloning and characterization of NADP-mannitol dehydrogenase cDNA from the button mushroom, Agaricus bisporus, and its expression in response to NaCl stress

Mannitol, a six-carbon sugar alcohol, is the main storage carbon in the button mushroom, Agaricus bisporus. Given the physiological importance of mannitol metabolism in growth, fruit body development, and salt tolerance of A. bisporus, the enzyme responsible for mannitol biosynthesis, NADP-dependent mannitol dehydrogenase (MtDH) (EC 1.1.1.138), was purified to homogeneity, and MtDH cDNA was cloned, sequenced, and characterized. To our knowledge, this represents the first report on the isolation of a cDNA encoding an NADP-dependent mannitol dehydrogenase. The MtDH cDNA contains an open reading frame of 789 bp encoding a protein of approximately 28 kDa. The N-terminal and internal amino acid sequences of the deduced protein exactly matched the ones determined from the purified MtDH subunit, whereas the amino acid composition of the deduced protein was nearly identical to that of the purified MtDH. The MtDH cDNA showed high homology with a plant-induced short-chain dehydrogenase from Uromyces fabae. Phylogenetic analysis based on amino acid sequences from mannitol(-1-phosphate) dehydrogenases indicated a close relationship between the substrate specificity of the enzymes and phylogenetic differentiation. Salt-stressed fruit bodies showed an overall increase in mannitol biosynthesis, as was evident from the increase in MtDH activity, MtDH abundance, and MtDH RNA accumulation. Furthermore, the MtDH transcript level seems to be under developmental control, as MtDH RNA accumulated during maturation of the fruit body.

The complete genome of Bacillus subtilis: from sequence annotation to data management and analysis

The completion of the entire 4.2-Mb genome sequence of the gram-positive bacterium Bacillus subtilis has been a milestone for biological studies on this model organism. This paper describes bioinformatics work related to this joint European and Japanese project: methods and strategies for gene annotation and detection of sequencing errors, using an integrated cooperative computer environment (Imagene); construction of a specialized database for data management and a WWW server for data retrieval (SubtiList); DNA sequence analysis, yielding striking results on oligonucleotide bias, repeated sequences, and codon usage, all landmarks of evolutionary events shaping the B. subtilis genome.

Effect of mutations in the transmethylase and dehydrogenase/chelatase domains of sirohaem synthase (CysG) on sirohaem and cobalamin biosynthesis

The Escherichia coli CysG protein (sirohaem synthase) catalyses four separate reactions that are required for the transformation of uroporphyrinogen III into sirohaem, initially two S-adenosyl-l-methionine-dependent transmethylations at positions 2 and 7, mediated through the C-terminal, or CysGA, catalytic domain of the protein, and subsequently a ferrochelation and dehydrogenation, mediated through the N-terminal, or CysGB, catalytic domain of the enzyme. This report describes how the deletion of the NAD+-binding site of CysG, located within the first 35 residues of the N-terminus, is detrimental to the activity of CysGB but does not affect the catalytic activity of CysGA, whereas the mutation of a number of phylogenetically conserved residues within CysGA is detrimental to the transmethylation reaction but does not affect the activity of CysGB. Further studies have shown that CysGB is not essential for cobalamin biosynthesis because the presence of the Salmonella typhimurium CobI operon with either cysGA or the Pseudomonas denitrificans cobA are sufficient for the synthesis of cobyric acid in an E. coli cysG deletion strain. Evidence is also presented to suggest that a gene within the S. typhimurium CobI operon might act as a chelatase that, at low levels of cobalt, is able to aid in the synthesis of sirohaem.

The Genome Sequence DataBase (GSDB): improving data quality and data access

In 1997 the primary focus of the Genome Sequence DataBase (GSDB; www. ncgr.org/gsdb ) located at the National Center for Genome Resources was to improve data quality and accessibility. Efforts to increase the quality of data within the database included two major projects; one to identify and remove all vector contamination from sequences in the database and one to create premier sequence sets (including both alignments and discontiguous sequences). Data accessibility was improved during the course of the last year in several ways. First, a graphical database sequence viewer was made available to researchers. Second, an update process was implemented for the web-based query tool, Maestro. Third, a web-based tool, Excerpt, was developed to retrieve selected regions of any sequence in the database. And lastly, a GSDB flatfile that contains annotation unique to GSDB (e.g., sequence analysis and alignment data) was developed. Additionally, the GSDB web site provides a tool for the detection of matrix attachment regions (MARs), which can be used to identify regions of high coding potential. The ultimate goal of this work is to make GSDB a more useful resource for genomic comparison studies and gene level studies by improving data quality and by providing data access capabilities that are consistent with the needs of both types of studies.

Nucleotide sequence and analysis of the phoB-rrnE-groESL region of the Bacillus subtilis chromosome

A 36 kb sequence of the phoB-rrnE-groESL region of the Bacillus subtilis chromosome at around 55 degrees has been determined. The sequenced region contains 36 ORFs including the phoB and groESL genes, and the whole rrnE operon. The phoB gene is transcribed in the direction opposite to that of chromosome replication, while most ORFs, including groESL and the rrnE operon, are transcribed in the same direction. Two newly identified tRNA genes upstream of the rrnE operon were those for Arg-tRNA and Gly-tRNA. The sequenced region contains an operon consisting of genes for degradation and uptake of mannan. The rrnE operon and its downstream ORFs are well conserved among Mycoplasma genitalium, Haemophilus influenzae, Synechocystis sp. and Methanococcus jannaschii. delta H consensus sequences are present in the promoter regions of three ORFs, including groESL.

Structure and mechanism of a sub-family of enzymes related to N-acetylneuraminate lyase

We describe here a sub-family of enzymes related both structurally and functionally to N-acetylneuraminate lyase. Two members of this family (N-acetylneuraminate lyase and dihydrodipicolinate synthase) have known three-dimensional structures and we now proceed to show their structural and functional relationship to two further proteins, trans-o-hydroxybenzylidenepyruvate hydratase-aldolase and D-4-deoxy-5-oxoglucarate dehydratase. These enzymes are all thought to involve intermediate Schiff-base formation with their respective substrates. In order to understand the nature of this intermediate, we have determined the three-dimensional structure of N-acetylneuraminate lyase in complex with hydroxypyruvate (a product analogue) and in complex with one of its products (pyruvate). From these structures we deduce the presence of a closely similar Schiff-base forming motif in all members of the N-acetylneuraminate lyase sub-family. A fifth protein, MosA, is also confirmed to be a member of the sub-family although the involvement of an intermediate Schiff-base in its proposed reaction is unclear.

Nitrogen deprivation of Anabaena sp. strain PCC 7120 elicits rapid activation of a gene cluster that is essential for uptake and utilization of nitrate

A transposon bearing luxAB, encoding luciferase, as a reporter of transcription was used to identify genes that are activated rapidly upon deprivation of Anabaena sp. strain PCC 7120 of fixed nitrogen. The three transposon-marked loci that were identified as responding most rapidly and strongly are closely linked and situated within nirA and nrtC and between nrtD and narB, genes whose products are responsible for uptake and reduction of NO2- and NO3-. A strain bearing a transcriptional fusion of narB to luxAB was constructed. Luminescence catalyzed by LuxAB was used to report on the expression of the interrupted genes. Whether these genes are regulated only coordinately is discussed.

Sequencing and functional analysis of the genome of Bacillus subtilis strain 168

The international programme to sequence the 4.2 Mb genome of Bacillus subtilis, a model Gram-positive bacterium, is a joint project involving European, Japanese and US research groups. To date ca. 3.0 Mb of the genome has been sequenced, with the remaining 1.2 Mb expected to be completed in 1997. The amenability of B.subtilis to genetic manipulation, combined with the availability of extensive expertise on its biochemistry and physiology, makes this bacterium a valuable organism in which to investigate the properties of genes for which functions cannot be readily ascribed by standard methods.

A new approach using multiplex long accurate PCR and yeast artificial chromosomes for bacterial chromosome mapping and sequencing

An efficient approach for structural studies on bacterial chromosomes is presented. It is based on high-resolution PCR map construction by using a multiplex long accurate PCR (MLA PCR) protocol and a YAC clone carrying the region to be mapped as indicator. The high-resolution PCR map of the bacillus subtilis rrnB-dnaB region is presented as an example. Data are also presented on the use of DNA generated by LA PCR for sequencing; they are relevant to LA PCR induced mutations and justify the application of such mapping for sequencing long stretches of bacterial chromosomes.

Sequencing and analysis of bacterial genomes

The complete sequences of two small bacterial genomes have recently become available, and those of several more species should follow within the next two years. Sequence comparisons show that the most bacterial proteins are highly conserved in evolution, allowing predictions to be made about the functions of most products of an uncharacterized genome. Bacterial genomes differ vastly in their gene repertoires. Although genes for components of the translation and transcription machinery, and for molecular chaperones, are typically maintained, many regulatory and metabolic systems are absent in bacteria with small genomes. Mycoplasma genitalium, with the smallest known genome of any cellular life form, lacks virtually all known regulatory genes, and its gene expression may be regulated differently than in other bacteria. Genome organization is evolutionarily labile: extensive gene shuffling leaves only very few conserved gene arrays in distantly related bacteria.

NRSub: a non-redundant database for Bacillus subtilis

In the context of the international project aimed at sequencing the whole genome of Bacillus subtilis we have developed a non-redundant, fully annotated database of sequences from this organism. Starting from the B.subtilis sequences available in the EMBL, GenBank and DDBJ collections we have removed all encountered duplications and then added extra annotations to the sequences (e.g. accession numbers for the genes, locations on the genetic map, codon usage, etc.) We have also added cross-references to the EMBL, MEDLINE, SWISS-PROT and ENZYME data banks. The present system results from merging of the NRSub and SubtiList databases and the sequence contigs used in the two systems are identical. NRSub is distributed as a flatfile in EMBL format (which is supported by most sequence analysis software packages) and as an ACNUC database, while SubtiList is distributed as a relational database under 4th Dimension. It is possible to access the data through two dedicated World Wide Web servers located in France and Japan.

I-CeuI recognition sites in the rrn operons of the Bacillus subtilis 168 chromosome: inherent landmarks for genome analysis

The Bacillus subtilis 168 circular chromosome yielded ten fragments on I-CeuI endonuclease digestion. I-CeuI recognizes a 26 bp sequence that is located within the gene encoding the 23S subunit of the rRNA in Chlamydomonas eugametos, Escherichia coli and Salmonella typhimurium. The precise locations of the I-CeuI sites of the B. subtilis chromosome were determined on a NotI-SfiI physical map by (i) double digestion analyses with I-CeuI and SfiI, (ii) comparison of mutant strains lacking a specific rrn operon, (iii) using an I-CeuI linking clone and (iv) analysis of nucleotide sequence data of some rrn operons. In conclusion, all the I-CeuI sites were located within the B. subtilis rrn operons and the I-CeuI sites were conserved in all the B. subtilis 168 derivatives tested. Thus, variations in size of the I-CeuI fragments must be due to genome alterations. A B. subtilis 168 strain was investigated with I-CeuI. We demonstrated that the aberrant structure was the outcome of the inversion of an approximately 1700 kb DNA segment.

The Bacillus subtilis genome project: aims and progress

The members of the bacterial genus Bacillus are important organisms for both research and industrial purposes, and a major international effort is under way to sequence the complete genome of Bacillus subtilis, the type species for this genus. In this article the organization of the project is summarized; the strategies employed for cloning, sequencing and data handling; the progress to date, and the likely benefits which will accrue to basic research and to the biotechnology industry upon completion of the sequence.

An estimation of minimal genome size required for life

The number of indispensable chromosomal loci for a bacterium, Bacillus subtilis was estimated. Seventy-nine randomly selected chromosomal loci were investigated by mutagenesis. Mutation at only six loci rendered B. subtilis unable to form colonies. In contrast, mutants for the rest of the 73 loci retained the ability to form colonies. Mutant B. subtilis with multiple-fold mutations of those dispensable loci (7-, 12- or 33-fold) were not impaired in their ability to form colonies on nutritionally adequate medium, indicating that up to 33 dispensable loci were simultaneously abolished. Given the statistical analyses for the frequency of indispensable loci (6 out of 79), total indispensable genetic material would be included within about 562 kbp. The hypothetical minimum genome size lies in the range of those currently determined smallest genomes for bacteria.