J. Arnau et Ki. Sorensen, THE ISOLATION OF NOVEL HEAT-SHOCK GENES IN LACTOCOCCUS-LACTIS USING RNA SUBTRACTIVE HYBRIDIZATION, Gene, 188(2), 1997, pp. 229-234
Lactococcus lactis is subjected to heat shock (hs) during cheese manuf
acturing. A number of conserved hs genes have been cloned and studied
in this organism, although no regulatory gene, e.g. alternative sigma
factor, has been identified. RNA subtractive hybridization was used to
identify genes expressed very early when L. lactis MG1363 was shifted
from 30 to 43 degrees C. P-32-labeled cDNA synthesized from RNA isola
ted from hs cells at 43 degrees C was mixed with an excess vegetative
RNA and the mixture was directly used as a probe after a short hybridi
zation step. Northern analysis revealed a moderate induction for the p
robes used, and low expression was also detected in non-hs cells, demo
nstrating the applicability of this technique for the detection of dif
ferentially expressed genes. The probes were used to identify genomic
library clones containing the corresponding genes. Among the five clon
es studied, a cell division operon including a putative ftsZ homolog (
pJAK2) was identified. Additionally, a putative hsp86 homolog (pJAK3),
three different transposase encoding genes (pJAK1 and pJAK3), a gene
coding for a deoR-like transcriptional repressor (pJAK4) and a putativ
e regulatory gene that showed homology to an alkaline shock protein (p
JAK5) were characterized.