Cloning and analysis of the L-lactate utilization genes from Streptococcus iniae.
The presence of lactate oxidase was examined in eight Streptococcus species and some related species of bacteria. A clone (pGR002) was isolated from a genomic library of Streptococcus iniae generated in Escherichia coli, containing a DNA fragment spanning two genes designated lctO and lctP. We show that these genes are likely to be involved in the L-lactic acid aerobic metabolism of this organism. This DNA fragment has been sequenced and characterized. A comparison of the deduced amino acid sequence of LctP protein demonstrated that the protein had significant homology with the L-lactate permeases of other bacteria. The amino acid sequence of the LctO protein of S. iniae also showed a strong homology to L-lactate oxidase from Aerococcus viridans and some NAD-independent lactate dehydrogenases, all belonging to the family of flavin mononucleotide-dependent alpha-hydroxyacid-oxidizing enzymes. Biochemical assays of the gene products confirm the identity of the genes from the isolated DNA fragment and reveal a possible role for the lactate oxidase from S. iniae. This lactate oxidase is discussed in relation to the growth of the organism in response to carbon source availability.
Gibello
A
A
Department of Microbiology, Institute of Food Research, Reading Laboratory, Reading RG6 6BZ. Gibelloa@eucmax.sim.ucm.es
Collins
M D
MD
Domínguez
L
L
Fernández-Garayzábal
J F
JF
Richardson
P T
PT
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics*; D001711:Biotransformation; D003001:Cloning, Molecular; D029968:Escherichia coli Proteins; D005798:Genes, Bacterial; D005947:Glucose / Q000494:pharmacology; D019344:Lactic Acid / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000235:genetics*; D006899:Mixed Function Oxygenases / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D013291:Streptococcus / Q000235:genetics* / Q000378:metabolism
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; C083722:LldP protein, E coli; D026901:Membrane Transport Proteins; D019344:Lactic Acid; D006899:Mixed Function Oxygenases; C021497:lactate 2-monooxygenase; D005947:Glucose