Lysis of an Lactococcus lactis Di-peptidase Mutant and Rescue by Mutation in the Pleiotropic Regulator CodY.

Lysis of an Lactococcus lactis Di-peptidase Mutant and Rescue by Mutation in the Pleiotropic Regulator CodY. Appl Environ Microbiol. 2020 Jan 31;: Authors: Huang C, Hernandez-Valdes JA, Kuipers OP, Kok J Abstract Lactococcus lactis subsp. cremoris MG1363 is a model for the lactic acid bacteria (LAB) used in the dairy industry. The proteolytic system, consisting of a proteinase, several peptide- and amino acid uptake systems and a host of intracellular peptidases, plays a vital role in nitrogen metabolism and is of eminent importance for flavor formation in dairy products. The dipeptidase PepV functions in the last stages of proteolysis. A link between nitrogen metabolism and peptidoglycan (PG) biosynthesis was underlined by the finding that deletion of the dipeptidase gene pepV (MGΔpepV) results in a prolonged lag phase when the mutant strain was grown with a high concentration of glycine. In addition, most MGΔpepV cells lyse and have serious defects in their shape. This phenotype is due to a shortage of alanine, since adding alanine can rescue the growth and shape defects. Strain MGΔpepV is more resistant to vancomycin, an antibiotic targeting peptidoglycan D-Ala-D-Ala ends, which confirmed that MGΔpepV has an abnormal PG composition. A mutant of MGΔpepV was obtained in which growth inhibition and cell shape defects were alleviated. Genome sequencing shows that this mutant has a single point mutation in the codY gene, resulting...
Source: Applied and Environmental Microbiology - Category: Microbiology Authors: Tags: Appl Environ Microbiol Source Type: research