TY - JOUR
T1 - AcmD, a homolog of the major autolysin AcmA of Lactococcus lactis, binds to the cell wall and contributes to cell separation and autolysis
AU - Visweswaran, Ganesh Ram R
AU - Steen, Anton
AU - Leenhouts, Kees
AU - Szeliga, Monika
AU - Ruban, Beata
AU - Hesseling-Meinders, Anne
AU - Dijkstra, Bauke W
AU - Kuipers, Oscar P
AU - Kok, Jan
AU - Buist, Girbe
PY - 2013/8/8
Y1 - 2013/8/8
N2 - Lactococcus lactis expresses the homologous glucosaminidases AcmB, AcmC, AcmA and AcmD. The latter two have three C-terminal LysM repeats for peptidoglycan binding. AcmD has much shorter intervening sequences separating the LysM repeats and a lower iso-electric point (4.3) than AcmA (10.3). Under standard laboratory conditions AcmD was mainly secreted into the culture supernatant. An L. lactis acmAacmD double mutant formed longer chains than the acmA single mutant, indicating that AcmD contributes to cell separation. This phenotype could be complemented by plasmid-encoded expression of AcmD in the double mutant. No clear difference in cellular lysis and protein secretion was observed between both mutants. Nevertheless, overexpression of AcmD resulted in increased autolysis when AcmA was present (as in the wild type strain) or when AcmA was added to the culture medium of an AcmA-minus strain. Possibly, AcmD is mainly active within the cell wall, at places where proper conditions are present for its binding and catalytic activity. Various fusion proteins carrying either the three LysM repeats of AcmA or AcmD were used to study and compare their cell wall binding characteristics. Whereas binding of the LysM domain of AcmA took place at pHs ranging from 4 to 8, LysM domain of AcmD seems to bind strongest at pH 4.
AB - Lactococcus lactis expresses the homologous glucosaminidases AcmB, AcmC, AcmA and AcmD. The latter two have three C-terminal LysM repeats for peptidoglycan binding. AcmD has much shorter intervening sequences separating the LysM repeats and a lower iso-electric point (4.3) than AcmA (10.3). Under standard laboratory conditions AcmD was mainly secreted into the culture supernatant. An L. lactis acmAacmD double mutant formed longer chains than the acmA single mutant, indicating that AcmD contributes to cell separation. This phenotype could be complemented by plasmid-encoded expression of AcmD in the double mutant. No clear difference in cellular lysis and protein secretion was observed between both mutants. Nevertheless, overexpression of AcmD resulted in increased autolysis when AcmA was present (as in the wild type strain) or when AcmA was added to the culture medium of an AcmA-minus strain. Possibly, AcmD is mainly active within the cell wall, at places where proper conditions are present for its binding and catalytic activity. Various fusion proteins carrying either the three LysM repeats of AcmA or AcmD were used to study and compare their cell wall binding characteristics. Whereas binding of the LysM domain of AcmA took place at pHs ranging from 4 to 8, LysM domain of AcmD seems to bind strongest at pH 4.
KW - COMPLETE GENOME SEQUENCE
KW - GRAM-POSITIVE BACTERIA
KW - ACID BACTERIUM
KW - N-ACETYLGLUCOSAMINIDASE
KW - ESCHERICHIA-COLI
KW - PEPTIDOGLYCAN HYDROLASE
KW - STREPTOCOCCUS-LACTIS
KW - BACILLUS-SUBTILIS
KW - LYSM DOMAINS
KW - EXPRESSION
U2 - 10.1371/journal.pone.0072167
DO - 10.1371/journal.pone.0072167
M3 - Article
C2 - 23951292
SN - 1932-6203
VL - 8
JO - PLoS ONE
JF - PLoS ONE
IS - 8
M1 - e72167
ER -