title: Importance of mycoloyltransferases on the physiology of Corynebacterium glutamicum.
abstract: Mycoloyltransferases (Myts) play an essential role in the biogenesis of the cell envelope of members of the Corynebacterineae, a group of bacteria that includes the mycobacteria and corynebacteria. While the existence of several functional myt genes has been demonstrated in both mycobacteria and corynebacteria (cmyt), the disruption of any of these genes has at best generated cell-wall-defective but always viable strains. To investigate the importance of Myts on the physiology of members of the Corynebacterineae, a double mutant of Corynebacterium glutamicum was constructed by deleting cmytA and cmytB, and the consequences of the deletion on the viability of the mutant, the transfer of corynomycoloyl residues onto its cell-wall arabinogalactan and trehalose derivatives, and on its cell envelope ultrastructure were determined. The double mutant strain failed to grow at 34 degrees C and exhibited a growth defect and formed segmentation-defective cells at 30 degrees C. Biochemical analyses showed that the double mutant elaborated 60 % less cell-wall-bound corynomycolates and produced less crystalline surface layer proteins associated with the cell surface than the parent and cmytA-inactivated mutant strains. Freeze-fracture electron microscopy showed that the DeltacmytA DeltacmytB double mutant, unlike the wild-type and cmytA-inactivated single mutant strains, frequently exhibited an additional fracture plane that propagated within the plasma membrane and rarely exposed the S-layer protein. Ultra-thin sectioning of the double mutant cells showed that they were totally devoid of the outermost layer. Complementation of the double mutant with the wild-type cmytA or cmytB gene restored completely or partially this phenotype. The data indicate that Myts are important for the physiology of C. glutamicum and reinforce the concept that these enzymes would represent good targets for the discovery of new drugs against the pathogenic members of the Corynebacterineae.
authors.affiliation: Département des Mécanismes Moléculaires des Infections Mycobactériennes, Institut de Pharmacologie et de Biologie Structurale, CNRS and Université Paul Sabatier (Unité Mixte de Recherche 5089), 205 route de Narbonne, 31077 Toulouse Cedex 04, France.
authors.forename: Raoudha
authors.initials: R
authors.lastname: Kacem
authors.affiliation: Laboratoire de Biotechnologie des Micro-organismes d'Intérêt Industriel, Institut de Génétique et Microbiologie, UMR 8621 du CNRS et de l'Université Paris-Sud, 91405 Orsay Cedex, France.
authors.forename: Célia
authors.initials: C
authors.lastname: De Sousa-D'Auria
authors.affiliation: Département des Mécanismes Moléculaires des Infections Mycobactériennes, Institut de Pharmacologie et de Biologie Structurale, CNRS and Université Paul Sabatier (Unité Mixte de Recherche 5089), 205 route de Narbonne, 31077 Toulouse Cedex 04, France.
authors.forename: Marielle
authors.initials: M
authors.lastname: Tropis
authors.affiliation: M.E. Müller Institute (MSB) Biozentrum, University of Basel, Klingelbergstr. 70, CH-4056 Basel, Switzerland.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Chami
authors.affiliation: Institut National de la Santé et de la Recherche Médicale (INSERM U 452), UFR de Médecine, 28 Avenue de Valombrose, 06107 Nice Cedex 02, France.|Institut Pasteur, Service de Microscopie électronique, 25 rue du Docteur Roux, 75724 Paris Cedex 15, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Gounon
authors.affiliation: Laboratoire de Biotechnologie des Micro-organismes d'Intérêt Industriel, Institut de Génétique et Microbiologie, UMR 8621 du CNRS et de l'Université Paris-Sud, 91405 Orsay Cedex, France.
authors.forename: Gérard
authors.initials: G
authors.lastname: Leblon
authors.affiliation: Laboratoire de Biotechnologie des Micro-organismes d'Intérêt Industriel, Institut de Génétique et Microbiologie, UMR 8621 du CNRS et de l'Université Paris-Sud, 91405 Orsay Cedex, France.
authors.forename: Christine
authors.initials: C
authors.lastname: Houssin
authors.affiliation: Département des Mécanismes Moléculaires des Infections Mycobactériennes, Institut de Pharmacologie et de Biologie Structurale, CNRS and Université Paul Sabatier (Unité Mixte de Recherche 5089), 205 route de Narbonne, 31077 Toulouse Cedex 04, France.
authors.forename: Mamadou
authors.initials: M
authors.lastname: Daffé
mesh_terms: D000217:Acyltransferases / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000378:metabolism; D003352:Corynebacterium / Q000201:enzymology* / Q000235:genetics / Q000502:physiology / Q000648:ultrastructure; D005614:Freeze Fracturing; D017353:Gene Deletion; D005798:Genes, Bacterial; D005816:Genetic Complementation Test; D008565:Membrane Proteins / Q000378:metabolism; D008854:Microscopy, Electron; D009171:Mycolic Acids / Q000378:metabolism; D010641:Phenotype
chemical_list: D001426:Bacterial Proteins; D008565:Membrane Proteins; D009171:Mycolic Acids; D000217:Acyltransferases