Outer-membrane lipoprotein LpoB spans the periplasm to stimulate the peptidoglycan synthase PBP1B.

Abstract : Bacteria surround their cytoplasmic membrane with an essential, stress-bearing peptidoglycan (PG) layer. Growing and dividing cells expand their PG layer by using membrane-anchored PG synthases, which are guided by dynamic cytoskeletal elements. In Escherichia coli, growth of the mainly single-layered PG is also regulated by outer membrane-anchored lipoproteins. The lipoprotein LpoB is required for the activation of penicillin-binding protein (PBP) 1B, which is a major, bifunctional PG synthase with glycan chain polymerizing (glycosyltransferase) and peptide cross-linking (transpeptidase) activities. Here, we report the structure of LpoB, determined by NMR spectroscopy, showing an N-terminal, 54-aa-long flexible stretch followed by a globular domain with similarity to the N-terminal domain of the prevalent periplasmic protein TolB. We have identified the interaction interface between the globular domain of LpoB and the noncatalytic UvrB domain 2 homolog domain of PBP1B and modeled the complex. Amino acid exchanges within this interface weaken the PBP1B-LpoB interaction, decrease the PBP1B stimulation in vitro, and impair its function in vivo. On the contrary, the N-terminal flexible stretch of LpoB is required to stimulate PBP1B in vivo, but is dispensable in vitro. This supports a model in which LpoB spans the periplasm to interact with PBP1B and stimulate PG synthesis.
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Proceedings of the National Academy of Sciences of the United States of America , National Academy of Sciences, 2014, 111 (22), pp.8197-202
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http://hal.univ-grenoble-alpes.fr/hal-01119756
Contributeur : Frank Thomas <>
Soumis le : mardi 24 février 2015 - 08:35:38
Dernière modification le : jeudi 15 mars 2018 - 16:56:04

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Alexander J F Egan, Nicolas L Jean, Alexandra Koumoutsi, Catherine M Bougault, Jacob Biboy, et al.. Outer-membrane lipoprotein LpoB spans the periplasm to stimulate the peptidoglycan synthase PBP1B.. Proceedings of the National Academy of Sciences of the United States of America , National Academy of Sciences, 2014, 111 (22), pp.8197-202. 〈hal-01119756〉

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