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Titolo:
Study of the duplicated glycolytic genes in Lactococcus lactis IL140
Autore:
Jamet, E; Ehrlich, SD; Duperray, F; Renault, P;
Indirizzi:
INRA, Lab Genet Microbienne, F-78352 Jouy En Josas, France INRA Jouy En Josas France F-78352 obienne, F-78352 Jouy En Josas, France CIRDC DANONE, F-92350 Le Plessis Robinson, France CIRDC DANONE Le PlessisRobinson France F-92350 Plessis Robinson, France
Titolo Testata:
LAIT
fascicolo: 1-2, volume: 81, anno: 2001,
pagine: 115 - 129
SICI:
0023-7302(200101/04)81:1-2<115:SOTDGG>2.0.ZU;2-A
Fonte:
ISI
Lingua:
FRE
Soggetto:
GRAM-POSITIVE BACTERIA; CATABOLITE REPRESSION; BACILLUS-SUBTILIS; ESCHERICHIA-COLI; YEAST ENOLASE; PROTEIN; OPERON; CCPA; ACTIVATION; SEQUENCE;
Keywords:
Lactococcus lactis; metabolism; glycolysis; regulation;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Agriculture,Biology & Environmental Sciences
Citazioni:
21
Recensione:
Indirizzi per estratti:
Indirizzo: Jamet, E INRA, Lab Genet Microbienne, Domaine de Vilvert, F-78352 Jouy En Josas, France INRA Domaine de Vilvert Jouy En Josas France F-78352 sas, France
Citazione:
E. Jamet et al., "Study of the duplicated glycolytic genes in Lactococcus lactis IL140", LAIT, 81(1-2), 2001, pp. 115-129

Abstract

The conversion of sugars into lactic acid is the main metabolic pathway providing energy to lactic acid bacteria. This conversion is also involved inproduction of different compounds participating to the organoleptic properties of fermented products. The L. lactis knowledge of the genome has giventhe access to sequences of genes encoding the enzymes involved in the two main metabolic pathways described for the fermentation of glucose in lacticacid bacteria: (1) the homofermentative pathway through glycolysis leadingto two lactate molecules per glucose consumed; (2) the heterofermentative pathway through the Pentose Phosphate pathway giving one lactate, one acetate and one CO2 per molecule of glucose. The research of the genes, corresponding to proteins involved in these metabolic pathways, revealed that some enzymes are encoded by 2 distinct genes. This fact could give to the cell the possibility to produce enzymes with different biochemical properties, orto control their expression according to specific conditions. Two copies of genes potentially encoding glyceraldehyde-3-phosphate dehydrogenase (gap)and enolase (eno) have been identified. Other microorganisms such as E. coli and B. subtilis also possess 2 gap genes sharing up to 60% homology, buthaving different functions. In L. lactis, gap1 and gap2 genes share around80% identity at both the nucleotidic and protein level. The analysis of codon usage, the transcription and the effect of genes inactivation shows that gap1 is the only gene involved in glycolysis. The transcription of this essential gene is very high during all phases of growth. Low increase of thelevel of transcription could be evidenced during growth in glucose, a sugar inducing the Catabolite Repression. Moreover, the presence of potential fixation site for CcpA (Cre box) upstream of initiation transcription box -35 suggests that gap1 transcription is activated by this protein. In contrast, the gap2 gene is dispensable and expressed at a very low level in our experimental conditions. Finally, in opposition to GapB from B. subtilis, theproduct of L. lactis gap2 might not to be involved in the neoglucogenesis.enoA and enoB genes are coding for proteins sharing 55% identity with known enolase. In opposition to the gap genes, the eno genes does not share significant nucleotidic homologies together. However, enoA presents 87% identity with the enolase genes from sequenced Streptococcus species whereas enoBpresents 95% identity with a plasmidic encoded gene isolated from Streptococcus thermophilus. These observations suggest that enoB was transferred from species to other. The analysis of codons bias strongly suggests that EnoA is the main glycolytic enolase. The transcription of these two genes is high during the exponential growth, 2 folds higher in glucose for enoA and similar during glucose or galactose fermentation for enoB. enoA and enoB seem transcribed simultaneously during the growth. These results suggest that both genes may play a significant role in the glycolysis.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 10/07/20 alle ore 09:17:52