Abstract
GPL X-1, a novel glycopeptidolipid (GPL) isolated from Mycobacterium xenopi (CIPT 140 35004), has recently been found to typify a new class of mycobacterial glycopeptidolipids devoid of C-mycoside core structure, the so-called serine-containing glycopeptidolipid [Rivière, M. & Puzo, G. (1991) J. Biol. Chem. 266, 9057-9063]. Here we report the purification and characterization of a novel serine-containing GPL termed GPL X-IIb, isolated from the M. xenopi strain NCTC 10042. On thin-layer chromatography, this GPL was found to be present in some other M. xenopi strains isolated from patients with pulmonary infections. The sugar and amino-acid compositions of this GPL were elucidated from the native form using a combination of two-dimensional homonuclear and heteronuclear scalar coupling NMR. The peptide and sugar sequences, as well as the methoxyl group locations on the C-3 of the 6-deoxy-alpha-L-talopyranoside (6dTalp) and on a Ser, were unambiguously determined by heteronuclear multiple-bond correlation experiments. GPL X-IIb was found to be composed of a lipotetrapeptide of the following structure C12-Ser-OMe-Ser-Phe-aThr-OMe (aThr = allothreonine). The sugar part is made up of 3OMe-alpha-L-6dTalp and the following disaccharide: alpha-L-Rhap-(1-->3)-2-O-Lau-alpha-L-Rhap (Rhap = rhanmopyranose). Unlike GPL X-I, the sugar attachment sites on the tetrapeptide were successfully determined from heteronuclear three-bond coupling correlation observed in the heteronuclear multiple bond correlation spectrum between the anomeric carbon resonances and the beta protons of aThr-OMe and Ser. It was established that the 3OMe-6dTalp glycosylates the Ser while the disaccharide is linked to the aThr-OMe. Thus both GPL X-I and GPL X-IIb share a common lipotetrapeptide core [with the exception of Ser(OMe)] but drastically differ in their oligosaccharide appendage. Thus, by analogy with the M. avium complex, the present report suggests that M. xenopi species can be divided in various serovars characterized by the unique structure of their C-mycoside GPL oligosaccharide appendage, enhancing the interest for this new type of serine-containing glycopeptidolipid.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
