A novel cytochrome c peroxidase from Neisseria gonorrhoeae: a lipoprotein from a Gram-negative bacterium

Abstract

A cytochrome c peroxidase (CCP) produced by Neisseria gonorrhoeae has been shown to have novel characteristics by investigating its location, expression and role in Neisseria gonorrhoeae and by expression in Escherichia coli. Analysis of the N-terminus of CCP indicated that it is a lipoprotein with a signal peptide for cleavage by signal peptidase II. Expression of the gonococcal CCP in E. coli revealed that it is first synthesized as a pro-apo-cytochrome that is translocated across the cytoplasmic membrane. The signal peptide is cleaved and haem is attached in the periplasm. The gonococcal CCP was associated with the membrane of both E. coli and N. gonorrhoeae. The expression of a MalE-CCP fusion protein has allowed characterization of CCP in vitro. Evidence is presented that CCP protects gonococci from hydrogen peroxide, presumably in the periplasmic compartment of the cell. The expression of CCP is dependent on the transcription factor FNR, but is repressed by nitrite, indicating that it could be most important in the stationary-phase response. These data support the hypothesis that the gonococcal lipoprotein CCP is anchored to the membrane in the periplasm, where it might be responsible for the reduction of hydrogen peroxide. Other putative CCP lipoproteins have been identified, representing a new subclass of bacterial CCP proteins.

Defenses against Oxidative Stress inNeisseria gonorrhoeae: a System Tailored for a Challenging Environment

“…The ccp gene of N. gonorrhoeae is located downstream of katA (see above), distal to a conserved hypothetical gene (213). An N. gonorrhoeae ccp mutant strain showed slight sensitivity to in vitro hydrogen peroxide killing relative to the wild-type strain; however, a ccp/katA double mutant strain was significantly more sensitive to in vitro hydrogen peroxide killing than was a katA mutant strain (213,239). Ccp belongs to class I of the peroxidase superfamily, along with catalase-peroxidases and ascorbate peroxidases (260).…”

“…2A) (153) that is involved in defense against hydrogen peroxide-induced killing has been reported (213,239). The ccp gene of N. gonorrhoeae is located downstream of katA (see above), distal to a conserved hypothetical gene (213).…”

“…FNR is essential for the gonococcal response to oxygen (153). Ccp of N. gonorrhoeae is expressed under conditions of low oxygen tension/anaerobiosis (153) and is dependent on FNR (239). Expression of ccp is also upregulated by hydrogen peroxide (226) and PerR (256).…”

“…Expression of ccp is also upregulated by hydrogen peroxide (226) and PerR (256). Ccp of N. gonorrhoeae is believed to be a lipoprotein, with a signal peptide for cleavage by signal peptidase II, that is anchored to the membrane in the periplasm (239). The lipid modification has been suggested as a way of maintaining the close proximity of Ccp to its c-type cytochrome electron donors located in, or associated with, the cytoplasmic membrane, while also maintaining it in a location where its protective mechanism is required (239).…”

Legless pathogens: how bacterial physiology provides the key to understanding pathogenicity

“…Gonococci defend themselves against attack from outside the cell by synthesizing a range of outer membrane redox proteins. These include an inducible cytochrome c peroxidase CCP and a constitutive c-type cytochrome, cytochrome c9 or CycP, which binds nitric oxide (Turner et al, 2003(Turner et al, , 2005. CycP is believed to act as a buffer system that limits damage by NO while the norB expression is induced (Anjum et al, 2002).…”