MOLECULAR ANALYSIS OF THE HSP (GROE) OPERON OF LEPTOSPIRA-INTERROGANSSEROVAR COPENHAGENI

A chromosomal gene library of Leptospira interrogans serovar copenhage ni strain Wijnberg was constructed in phage lambda gt11. Plaque immuno assay with RalphaP64 antiserum identified one clone expressing a putat ive groEL homologue. DNA sequence analysis of the 2.4 kb EcoRI-BamHI c loned fragment from strain Wijnberg revealed two open reading frames e ncoding polypeptides of 10.5 kDa (Hsp10) and 58 kDa (Hsp58). Sequence comparison of the deduced amino acid sequences of these ORFs confirmed the operon as the groE equivalent of Leptospira. Transcriptional anal ysis suggested that this operon is primarily under the control of an E sigma70 promoter element. However, both Hsp10 and Hsp58 were overexpre ssed under heatshock conditions as determined by [S-35]-methionine pul se labelling experiments. As no functional heat-shock promoter could b e identified, a 9bp inverted repeat, located between the transcription and translation start sites, may play a role in the upregulation of t his operon under heat-shock conditions, similar to mechanisms describe d for several Gram-positive organisms.