Biological and Chemical Adaptation to Endogenous Hydrogen Peroxide Production in D39.

The catalase-negative, facultative anaerobe D39 is naturally resistant to hydrogen peroxide (HO) produced endogenously by pyruvate oxidase (SpxB). Here, we investigate the adaptive response to endogenously produced HO. We show that lactate oxidase, which converts lactate to pyruvate, positively impacts pyruvate flux through SpxB and that mutants produce significantly lower HO.

An essential role for bacterial nitric oxide synthase in Staphylococcus aureus electron transfer and colonization.

Nitric oxide (NO) is a ubiquitous molecular mediator in biology. Many signalling actions of NO generated by mammalian NO synthase (NOS) result from targeting of the haem moiety of soluble guanylate cyclase. Some pathogenic and environmental bacteria also produce a NOS that is evolutionary related to the mammalian enzymes, but a bacterial haem-containing receptor for endogenous enzymatically generated NO has not been identified previously.

Instability of ackA (acetate kinase) mutations and their effects on acetyl phosphate and ATP amounts in Streptococcus pneumoniae D39.

Acetyl phosphate (AcP) is a small-molecule metabolite that can act as a phosphoryl group donor for response regulators of two-component systems (TCSs). The serious human respiratory pathogen Streptococcus pneumoniae (pneumococcus) synthesizes AcP by the conventional pathway involving phosphotransacetylase and acetate kinase, encoded by pta and ackA, respectively. In addition, pneumococcus synthesizes copious amounts of AcP and hydrogen peroxide (H(2)O(2)) by pyruvate oxidase, which is encoded by spxB.

Biosynthesis of Histidine.

The biosynthesis of histidine in Escherichia coli and Salmonella typhimurium has been an important model system for the study of relationships between the flow of intermediates through a biosynthetic pathway and the control of the genes encoding the enzymes that catalyze the steps in a pathway. This article provides a comprehensive review of the histidine biosynthetic pathway and enzymes, including regulation of the flow of intermediates through the pathway and mechanisms that regulate the amounts of the histidine biosynthetic enzymes. In addition, this article reviews the structure and regulation of the histidine (his) biosynthetic operon, including transcript processing, Rho-factor-dependent "classical" polarity, and the current model of his operon attenuation control.

Polymorphism and regulation of the spxB (pyruvate oxidase) virulence factor gene by a CBS-HotDog domain protein (SpxR) in serotype 2 Streptococcus pneumoniae.

spxB-encoded pyruvate oxidase is a major virulence factor of Streptococcus pneumoniae. During aerobic growth, SpxB synthesizes H2O2 and acetyl phosphate, which play roles in metabolism, signalling, and oxidative stress. We report here the first cis- and trans-acting regulatory elements for spxB transcription.