Info

Genomes of Pathogenic Neisseria Species

So far, the genome sequences of one N. gonorrhoeae [11] and three N. meningitidis strains [12-14] have been fully determined by the random shotgun sequencing strategy and made publicly available. However, only the annotation of the genome sequences of N. meningitidis serogroup A strain Z2491 [12] and N. meningitidis serogroup B strain MC58 [13] have been published. That of N. gonorrhoeae strain FA1090 is currently accessible via the homepage of the Los Alamos National Laboratory Bioscience Division (http://www.stdgen.lanl.gov/stdgen/bacteria/ngon/) [11]. Accordingly, only a preliminary annotation of N. meningitidis serogroup C strain FAM18 is currently available from the Wellcome Trust Sanger Institute homepage (accessible via http://www.sanger.ac.uk/Projects/N_meningitidis/ seroC/seroC.shtml) [14]. Among the nonpathogenic Neisseria species, shotgun sequencing of a N. lactamica (an ST-640 strain) genome at the Wellcome Trust Sanger Institute is complete, and finishing and gap closure of 38 contigs with a total size of 2.219 Mbp are in progress at the time of writing.

A summary of the overall features of the four completely sequenced and publicly available neisserial genomes is given in Table 11.1 and a multiple whole-genome alignment in Fig. 11.1. The three meningococcal genomes are all of quite similar size, around 2.22 Mbp, which is slightly larger than that of N.gonorrhoeae strain FA1090 with its 2.15 Mbp, and half the size of, e. g., the E. coli K12 genome with its 4.64 Mbp [15]. The average meningococcal open reading frame (ORF) length is 879 bp, compared to 827 bp in N. gonorrhoeae, and the coding density is between 83% and 84%. On the basis of the primary annotations [12, 13, 16], biological roles could be assigned to about 60% of all ORFs. Regarding those cate gories that are potentially important for the pathogenesis of neisserial diseases, 56% of all ORFs code for cell envelope proteins, 5-6 % for proteins involved in transport and binding functions, and another 3% belong to the category of mobile and extrachromosomal element functions. Finally, the genomes contain each four copies of a 16S-23S-5S ribosomal RNA operon and between 55 and 58 tRNAs.

0 0

Post a comment