Changes in gene transcription and protein expression involved in the response of Agrobacterium sp. ATCC 31749 to nitrogen availability during curdlan production.

The changes in transcription of genes involved in nitrogen metabolism and curdlan biosynthesis, and total protein expression were firstly analyzed to define the responses of Agrobacterium sp. ATCC 31749 to nitrogen source availability during curdlan fermentation. The transcription of all nitrogen metabolism and regulation genes increased significantly under nitrogen limitation. The genes of carbon (exoC) and nitrogen (ntrB, ntrC, and nifR) metabolism showed distinctive transcriptional responses to nitrogen limitation. Their relative expression level was increased by 14, 9, 7 and 7-fold, respectively. Two-dimentional electrophoresis (2-DE) revealed that the expression of 14 proteins were elevated and 6 proteins were down-regulated significantly under nitrogen starvation. Furthermore, 4 proteins (GroEL, ABC transporter, Atu1730 and enoyl-acyl carrier protein reductase) in which the expression level changed significantly were identified. The results showed that Agrobacterium sp. regulates its carbon flux and nitrogen assimilation effectively for better survival.