PUB - Publikationen an der Universität Bielefeld

The phosphate (P-i) starvation stimulon of Corynebacterium glutamicum was characterized by global gene expression analysis by using DNA microarrays. Hierarchical cluster analysis of the genes showing altered expression 10 to 180 min after a shift from P-i-sufficient to P-i-limiting conditions led to identification of five groups comprising 92 genes. Four of these groups included genes which are not directly involved in P metabolism and changed expression presumably due to the reduced growth rate observed after the shift or to the exchange of medium. One group, however, comprised 25 genes, most of which are obviously related to phosphorus (P) uptake and metabolism and exhibited 4- to >30-fold-greater expression after the shift to P-i limitation. Among these genes, the RNA levels of the pstSCAB (ABC-type P-i uptake system), glpQ (glycero-phosphoryldiester phosphodiesterase), ugpAEBC (ABC-type sn-glycerol 3-phosphate uptake system), phoH (unknown function), nucH (extracellular nuclease), and Cg10328 (5'-nucleotidase or related esterase) genes were increased, and pstSCAB exhibited a faster response than the other genes. Transcriptional fusion analyses revealed that elevated expression of pstSCAB and ugpAEBC was primarily due to transcriptional regulation. Several genes also involved in P uptake and metabolism were not affected by P-i starvation; these included the genes encoding a PitA-like P-i uptake system and a putative Na+-dependent P-i transporter and the genes involved in the metabolism of pyrophosphate and polyphosphate. In summary, a global, time-resolved picture of the response of C. glutamicum to P-i starvation was obtained.