Expression analysis of the csp-like genes from Corynebacterium glutamicum encoding homologs of the Escherichia coli major cold-shock protein cspA.
Three csp-like genes were identified in the Corynebacterium glutamicum genome and designated cspA, cspB, and cspA2. The genes cspA and cspA2 encode proteins, comprising of 67 amino acid residues, respectively. They share 83% identity with each other. Identity of those proteins with Escherichia coli Csp proteins was near 50%. The cspB gene encodes a protein composed of 127 amino acids, which has 40% and 35% sequence identity with CspA and CspA2, respectively, especially at its N-terminal region. Analysis of the gene expression profiles was done using transcriptional cat fusion, which identified not only active expression of the three genes at the physiological growth temperature of 30 degrees C but also growth phase-dependent expression with the highest activity at late log phase. The promoters of cspA and cspA2 were more active than that of cspB. The expression of the two genes increased by 30% after a temperature downshift to 15 degrees C, and such stimulation was more evident in the late growth phase. In addition, the cspA gene appeared to show DNA-binding activity in vivo, and the activity increased at lower temperatures. Interestingly, the presence of cspA in multicopy hindered the growth of the host C. glutamicum cells at 20 degrees C, but not at 30 degrees C. Altogether, these data suggest that cspA, cspB, and cspA2 perform functions related to cold shock as well as normal cellular physiology. Moreover, CspA and its ortholog CspA2 may perform additional functions as a transcriptional regulator.
Department of Biotechnology and Bioinformatics, Korea University, Chungnam 339-700, Korea.
Wan-Soo
WS
Kim
Soo-Dong
SD
Park
Seok-Myung
SM
Lee
Younhee
Y
Kim
Pil
P
Kim
Heung-Shick
HS
Lee
D019677:Artificial Gene Fusion; D001426:Bacterial Proteins / Q000096:biosynthesis* / Q000235:genetics; D015500:Chloramphenicol O-Acetyltransferase / Q000032:analysis / Q000235:genetics; D048230:Corynebacterium glutamicum / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics; D020869:Gene Expression Profiling; D017930:Genes, Reporter; D006360:Heat-Shock Proteins / Q000096:biosynthesis* / Q000235:genetics; D011485:Protein Binding; D013696:Temperature; D014157:Transcription Factors / Q000096:biosynthesis* / Q000235:genetics
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D006360:Heat-Shock Proteins; D014157:Transcription Factors; C062260:cold shock protein CS7.4, Bacteria; C077188:cold-shock protein CspB, Bacteria; D015500:Chloramphenicol O-Acetyltransferase