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Institut de Biologie StructuraleGrenoble / France

Innovative and specific painting of the pneumococcal surface

Peptidoglycan (PG) is the star molecule of the bacterial wall. In Gram-positive bacteria, teichoic acids (TA) are much less famous, although they account for about half the mass of surface molecules. These glycopolymers, anchored on the plasma membrane or on the PG, are decorated in pneumococcus with phosphorylcholines (PCho). This property was exploited to label the TA so that they could be located and tracked during the cell cycle. The labelling is carried out in two simple steps: culture of pneumococci in the presence of Propargyl-choline then coupling of modified PCho linked to TA with a fluorophore by click chemistry. This efficient and specific labelling, carried out on living bacteria, revealed the probable co-location of molecular machines for the synthesis of PG and TA. It also allows detection of the pneumococcus amongst a bacterial mixture, a pre-requisite for medical diagnostic (Figure). This work initiated within the IBS Pneumococcal Group benefited from an excellent partnership with the Département de Pharmacochimie Moléculaire of the UGA and from a significant contribution to molecular analyses from collaborators in Germany.

Specific and spatial labeling of choline-containing teichoic acids in Streptococcus pneumoniae by click chemistry. Di Guilmi AM, Bonnet J, Peiβert S, Durmort C, Gallet B, Vernet T, Gisch N, Wong YS. Chemical Commununications (Camb);53(76):10572-10575