New insights into the biogenesis of the cell envelope of corynebacteria: identification and functional characterization of five new mycoloyltransferase genes in Corynebacterium glutamicum.
Mycolic acids, the major lipid constituents of Corynebacterineae, play an essential role in maintaining the integrity of the bacterial cell envelope. We have previously characterized a corynebacterial mycoloyltransferase (PS1) homologous in its N-terminal part to the three known mycobacterial mycoloyltransferases, the so-called fibronectin-binding proteins A, B and C. The genomes of Corynebacterium glutamicum (ATCC13032 and CGL2005) and Corynebacterium diphtheriae were explored for the occurrence of other putative corynebacterial mycoloyltransferase-encoding genes (cmyt). In addition to csp1 (renamed cmytA), five new cmyt genes (cmytB-F) were identified in the two strains of C. glutamicum and three cmyt genes in C. diphtheriae. In silico analysis showed that each of the putative cMyts contains the esterase domain, including the three key amino acids necessary for the catalysis. In C. glutamicum CGL2005 cmytE is a pseudogene. The four new cmyt genes were disrupted in this strain and overexpressed in the inactivated strains. Quantitative analyses of the mycolate content of all these mutants demonstrated that each of the new cMyt-defective strains, except cMytC, accumulated trehalose monocorynomycolate and exhibited a lower content of covalently bound corynomycolate than did the parent strain. For each mutant, the mycolate content was fully restored by complementation with the corresponding wild-type gene. Finally, complementation of the cmytA-inactivated mutant by the individual new cmyt genes established the existence of two classes of mycoloyltransferases in corynebacteria.
De Sousa-D'Auria
Célia
C
Laboratoire de Biotechnologie des Microorganismes d'Intérêt Industriel, Institut de Génétique et Microbiologie, UMR 8621 du CNRS et de l'Université Paris-Sud, 91405 Orsay, France.
Kacem
Raoudha
R
Puech
Virginie
V
Tropis
Marielle
M
Leblon
Gérard
G
Houssin
Christine
C
Daffé
Mamadou
M
D000217:Acyltransferases / Q000235:genetics* / Q000378:metabolism*; D018829:Adhesins, Bacterial; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D002473:Cell Wall / Q000201:enzymology*; D003352:Corynebacterium / Q000166:cytology / Q000201:enzymology* / Q000235:genetics; D003353:Corynebacterium diphtheriae / Q000201:enzymology / Q000235:genetics; D016680:Genome, Bacterial; D050356:Lipid Metabolism; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009171:Mycolic Acids / Q000378:metabolism*; D010641:Phenotype
D018829:Adhesins, Bacterial; D001426:Bacterial Proteins; D002352:Carrier Proteins; D009171:Mycolic Acids; C078635:fibronectin-binding proteins, bacterial; D000217:Acyltransferases