The galU gene expression in Streptococcus pneumoniae

Abstract

The polysaccharide capsule of Streptococcus pneumoniae is the main virulence factor making the bacterium resistant to phagocytosis. The galU gene of Streptococcus pneumoniae encodes a UDP-glucose pyrophosphorylase absolutely required for capsule biosynthesis. In silico analyses indicated that galU gene is co-transcribed with the gpdA gene and four putative promoter regions located upstream gpdA were predicted. One of them behaved as a functional promoter in a promoter reporter system. It is conceivable that the sequence responsible for initiating transcription of gpdA-galU operon is an extended -10 site TATGATA(T/G)AAT. Semiquantitative real-time reverse transcription PCR experiments indicated that galU was expressed mainly in the exponential phase of growth.