Regulation of proteinase synthesis in Lactococcus lactis

Abstract

The synthesis of extracellular serine proteinase of Lactococcus lactis was studied during the growth in a batch and a continuous culture on chemically defined media. In a batch culture the proteinase synthesis started during the exponential phase of growth and the highest proteinase concentrations were found at the end of the exponential and beginning of the stationary phase of growth. During the growth in a lactose-limited chemostat with amino acids as the sole source of nitrogen, the specific rate of proteinase synthesis was maximal at a p of 0.23 h-I. At higher growth rates the proteinase production declined. The proteinase synthesis was dependent on the amino acid sources in the medium. In batch cultures of L. Iuctis grown on a chemically defined medium with amino acids, the proteinase production was increased four-fold compared to media containing casein or a tryptic digest of casein as the sole source of nitrogen. The inhibition of the rate of proteinase synthesis by casein and peptides was also observed during the growth in a chemostat.The addition of the dipeptide leucylproline (final concentration of 100 pM) to a lactose-limited continuous culture during the steady state (D = 0.23 h-I) resulted in a transient inhibition of the rate of proteinase synthesis. This suggested that exogenously supplied peptides control the regulation of proteinase synthesis of L. luctis.

Medium-dependent regulation of proteinase gene expression in Lactococcus lactis: control of transcription initiation by specific dipeptides

“…After growth in low-nitrogen media, the AlaT Ϫ DtpT Ϫ mutant exhibited higher levels of ␤-glucuronidase activity than did the wild-type (Table 3), which can be explained by its lower growth rate than that of the wild type (22). A regulatory role of peptides, and in particular of the dipeptide leucylproline, in proteinase production in L. lactis Wg2 has previously been suggested (21). However, in these experiments, proteinase production was found to be inhibited long after the addition of (di)peptides to the culture.…”

“…A different growth rate dependency has been observed for synthesis of L. lactis Wg2 proteinase, the level of which in continuous cultures with amino acids as the sole nitrogen source was found to be maximal at a dilution rate of 0.23 h Ϫ1 but decreased at higher dilution rates (21).…”

“…Strains AM1, E8, and Wg2 produced more proteinase in milk than in laboratory media (14,15). It has also been reported that proteinase production in strain Wg2 is dependent on both the nitrogen source and growth phase (21). Recently, the regulation of L. lactis SK11 proteinase production in different lactococcal strains has been analyzed by using multicopy plasmids containing the prtP gene (2).…”

Identical transcriptional control of the divergently transcribed prtP and prtM genes that are required for proteinase production in lactococcus lactis SK11

“…The structural prtP gene encodes the proteinase precursor, with a size of approximately 200 kDa, that has homology to the subtilisin family of serine proteases (28, 36). The prtM gene encodes a trans-acting maturase, a lipoprotein of 33 kDa, that is required for the activation of the inactive proteinase precursor (9, 37).Until now, a limited number of studies have dealt with the regulation of proteinase production in lactococci (3,7,11,12,20,22). The results of these investigations showed that proteinase production is mainly dependent on medium composition.…”

An Adaptation Strategy to Improve the Proteolytic Activities of Lactic Acid Bacteria Isolated From Pickles

“…This mechanism works through the synthesis of specific enzymes as a response to the stimulus of different environments (Murray et al, 2004;Tunail, 2009). In addition, previous studies have shown that a medium can regulate proteinase activity (Exterkate, 1979;Hugenholtz et al, 1984;Laan et al, 1993;Marugg et al, 1995;Meijer et al, 1996;Smid and Konings, 1990). Daeschel et al (1987) indicated that LAB of a vegetable origin have limited or no proteolytic activity and their amino acid degradation ability is lower compared to other microorganisms.…”