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The membrane-bound H(+)-ATPase complex is essential for growth of Lactococcus lactis.

ABSTRACT: The eight genes which encode the (F(1)F(o)) H(+)-ATPase in Lactococcus lactis subsp. cremoris MG1363 were cloned and sequenced. The genes were organized in an operon with the gene order atpEBFHAGDC; i.e., the order of atpE and atpB is reversed with respect to the more typical bacterial organization. The deduced amino acid sequences of the corresponding H(+)-ATPase subunits showed significant homology with the subunits from other organisms. Results of Northern blot analysis showed a transcript at approximately 7 kb, which corresponds to the size of the atp operon. The transcription initiation site was mapped by primer extension and coincided with a standard promoter sequence. In order to analyze the importance of the H(+)-ATPase for L. lactis physiology, a mutant strain was constructed in which the original atp promoter on the chromosome was replaced with an inducible nisin promoter. When grown on GM17 plates the resulting strain was completely dependent on the presence of nisin for growth. These data demonstrate that the H(+)-ATPase is essential for growth of L. lactis under these conditions.

SUBMITTER: Koebmann BJ

PROVIDER: S-EPMC111348 | biostudies-literature | 2000 Sep

REPOSITORIES: biostudies-literature

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The membrane-bound H(+)-ATPase complex is essential for growth of Lactococcus lactis.

Koebmann B J BJ Nilsson D D Kuipers O P OP Jensen P R PR

Journal of bacteriology 20000901 17

The eight genes which encode the (F(1)F(o)) H(+)-ATPase in Lactococcus lactis subsp. cremoris MG1363 were cloned and sequenced. The genes were organized in an operon with the gene order atpEBFHAGDC; i.e., the order of atpE and atpB is reversed with respect to the more typical bacterial organization. The deduced amino acid sequences of the corresponding H(+)-ATPase subunits showed significant homology with the subunits from other organisms. Results of Northern blot analysis showed a transcript at ...[more]

PMID: 10940012

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Project description:The development of transcriptomic tools has allowed exhaustive description of stress responses. These responses always superimpose a general response associated to growth rate decrease and a specific one corresponding to the stress. The exclusive growth rate response can be achieved through chemostat cultivation, enabling all parameters to remain constant except the growth rate. We analysed metabolic and transcriptomic responses of Lactococcus lactis in continuous cultures at different growth rates ranging from 0.09 to 0.47 h-1. Growth rate was conditioned by isoleucine supply. Although the metabolism was constant and homolactic, a widespread transcriptomic response involving 30 % of the genome was observed. The expression of genes encoding physiological functions associated with biogenesis increased with growth rate (transcription, translation, fatty acid and phospholipids metabolism). Many phages, prophages and transposons related genes were down regulated by growth rate suggesting genome plasticity to be involved in the adaptation to slow growth. The growth rate response was compared to carbon and amino-acid starvation transcriptomic responses, revealing constant and significant involvement of growth rate regulations in these two stressful conditions (overlap 26%). Although stringent response mechanism is considered as the one governing growth deceleration in bacteria, the rigorous comparison of the two transcriptomic responses clearly indicated the mechanisms are distinct. Moreover it was established that genes positively regulated by growth rate are preferentially located in the vicinity of replication origin while those negatively regulated are mainly encountered at the opposite. This result demonstrates the often neglected relationship between genes expression and their location on chromosome. Keywords: growth rate impact, continuous cultures Continuous cultivation of Lactococcus lactis IL1403 were carried out on a chemically defined medium and under controlled conditions (30 Â°C, pH 6.6, nitrogen atmosphere). Cell samples were harvested at steady state. Total RNA was extracted from these samples and radiolabelled cDNA were prepared and hybridized on nylon arrays. 1948 amplicons specific of Lactococcus lactis IL1403 genes were spotted twice on the array. Samples corresponding to various growth rates were analyzed simultaneously and 3 independent repetitions were performed.

Dataset Information

The membrane-bound H(+)-ATPase complex is essential for growth of Lactococcus lactis.

Publications

The membrane-bound H(+)-ATPase complex is essential for growth of Lactococcus lactis.

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