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The genome of Neisseria meningitidis serogroup B strain MC58 contains three genes - nmb0278, nmb0294 and nmb0407 - encoding putative homologues of DsbA, a periplasmic thiol disulphide oxidoreductase protein-folding catalyst of the Dsb protein family. DsbA assists the folding of periplasmic and membrane proteins in diverse organisms. While all three cloned genes complemented the DTT sensitivity of dsbA-null Escherichia coli, they showed different activities in folding specific target proteins in this background. NMB0278 protein was the most active in complementing defects in motility and alkaline phosphatase activity, while NMB0294 was the most active in folding periplasmic MalF. NMB0407 showed the weakest activity in all assays. It is extremely unusual for organisms to contain more than one chromosomal dsbA. Among the members of the genus Neisseria, only the meningococcus carries all three of these genes. Strains of Neisseria gonorrhoeae, Neisseria lactamica, Neisseria cinerea and Neisseria polysaccharea contained only homologues of nmb0278 and nmb0407, while Neisseria flava, Neisseria subflava and Neisseria flavescens carried only nmb0294. It is speculated that the versatility of the meningococcus in surviving in different colonizing and invasive disease settings may be derived in part from an enhanced potential to deploy outer-membrane proteins, a consequence of carrying an extended repertoire of protein-folding catalysts. [ABSTRACT FROM AUTHOR]

Previously, the authors have shown that inactivation of Shigella flexneri yihE, a gene of unknown function upstream of dsbA, which encodes a periplasmic disulphide catalyst, results in a global change of gene expression. Among the severely down-regulated genes are galETKM, suggesting that the yihE mutant, Sh54, may inefficiently produce the UDP-glucose and UDP-galactose required for LPS synthesis. This paper demonstrates that LPS synthesis in Sh54 is impaired. As a result, Sh54 is unable to polymerize host cell actin, due to aberrant localization of IcsA, or to cause keratoconjunctivitis in guinea pigs. Furthermore, Sh54 is more sensitive to some antimicrobial agents, and exhibits epithelial cytotoxicity characteristic of neither wild-type nor dsbA mutants. Supplying galETK in trans restores LPS synthesis and corrects all the defects. Hence, it is clear that the Shigella yihE gene is important not only in regulating global gene expression, as shown previously, but also in virulence through LPS synthesis via regulating the expression of the galETK operon. [ABSTRACT FROM AUTHOR]

Studies the copper and zinc-containing superoxide dismutases ([Cu,Zn]-SODs) in the Haemophilus-Actinobacillus-Pasteurella (HAP) group of bacteria. Isolation of sodC gene through polymerase chain reaction-based (PCR) approach; Cloning and sequencing of the five candidate sodC PCR fragments; Differences in the prokaryotic and eukaryotic examples of [Cu,Zn]-SODs.

The article presents a study on the possibility of setting the meningococcal biofilm growth as model for epithelial colonization. Neisseria meningitidis (N. meningitidis) invades the human nasopharynx with the possibility of life-threatening infection, and carriage of such is believed to lead to specific meningococal diseases immunity. Such aggregated organisms cling to the epithelial surface of the nasopharynx. A hypothesis is presented wherein the state when aggregated organisms attach to the epithelial surface is the biofilm state, and to further explore the this state, biofilm formation by a serogroup on an abiotic surface of a sorbarod system was investigated.

Investigates the role of periplasmic copper- and zinc-cofactored superoxide dismutase in the virulence of Salmonella choleraesuis. Enhancement of sensitivity to superoxide; Effect of the acquisition of sodC-1 on a bacteriophage; Result of loss of sodC gene.