Proline biosynthesis in Streptococcus thermophilus: characterization of the proBA operon and its products

Abstract

The presence of proline in the medium was not essential for growth of Streptococcus thermophilus, indicating that there is a proline biosynthetic pathway in this organism. Genetic and biochemical analysis identified and characterized this pathway. Two genes, designated pmB and pmA, were cloned, sequenced and characterized. Biochemical analysis of the pmB-and pmA-encoded enzymes showed that the proline biosynthetic pathway of s 8 thennophilus is similar t o the one previously described in Escherichia coli. The deduced amino acid sequence of a 2408 kb DNA region containing the genes revealed the similarity of the s 8 thennophilus gene products to ProB and ProA of E. coli and Serratia marcescens, and to the corresponding N-and C-terminal domains of the bifunctional plant enzyme A1-pyrroline-5-carboxylate synthetase of Wgna aconitifolia. Northern blot analysis showed that the two genes in 5. thennqphilus are organized in a single operon with pmB proximal and pmA distal t o the promoter; primer extension analysis indicated that pmBA transcription is not under repressive control by exogenously supplied proline.

Aspartate Biosynthesis Is Essential for the Growth of Streptococcus thermophilus in Milk, and Aspartate Availability Modulates the Level of Urease Activity

“…Genomic analysis of S. thermophilus has revealed that it has maintained the capacity to synthesize several amino acids throughout evolution (16). Despite the relevance of amino acid biosynthetic pathways in milk adaptation of S. thermophilus, only the functionality of genes involved in branched-chain-amino-acid, proline, and glutamine biosynthesis was experimentally investigated in this species (13,20,24).…”

“…Some S. thermophilus strains appear auxotrophic for at least four amino acids, Glu, Cys, His, and Met, while other lactic acid bacteria are known to be more exigent (16,19). The relevance of the amino acid biosynthetic pathways for the metabolism of S. thermophilus have been investigated for branched-chain amino acids, proline, and glutamine (13,20,24). S. thermophilus genome analysis has revealed a relatively high conservation of functional amino acid biosynthetic genes, which might reflect the importance of amino acid synthesis for the growth of this species in milk (2,16).…”

MarR-Like Transcriptional Regulator Involved in Detoxification of Aromatic Compounds in Sulfolobus solfataricus

“…To determine the first transcribed nucleotide, total RNA extracted from cells grown in the presence or in the absence of benzaldehyde and harvested at 0.3 OD 600 units was subjected to primer extension analysis as described in Limauro et al (38), using the primer 5Ј-GGTACTGAAATGA GGTAAAGGGG-3Ј, annealing from position ϩ160 to position ϩ139 in the Sso1351 gene. The same primer was used to produce a sequence ladder by using a Sequenase version 2.0 sequencing kit (Amersham) according to the manufacturer instructions to locate the products on 6% urea-polyacrylamide gel.…”

The specificity of oligopeptide transport by Streptococcus thermophilus resembles that of Lactococcus lactis and not that of pathogenic streptococci

“…Streptococcus thermophilus is able to synthesize several amino acids Limauro et al, 1996). This bacterium is therefore much less nutritionally demanding than other lactic acid bacteria (Bellengier et al, 1997;Chervaux et al, 2000;Hebert et al, 2000;van Niel & HahnHägerdal., 1999).…”