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Structure. 2014 Jul 8;22(7):1047-54. doi: 10.1016/j.str.2014.04.017. Epub 2014 Jun 19.

Elongated structure of the outer-membrane activator of peptidoglycan synthesis LpoA: implications for PBP1A stimulation.

Author information

1
University Grenoble Alpes, Institut de Biologie Structurale, F-38027 Grenoble, France; CEA, DSV, Institut de Biologie Structurale, F-38027 Grenoble, France; CNRS, Institut de Biologie Structurale, F-38027 Grenoble, France.
2
The Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Richardson Road, Newcastle upon Tyne NE2 4AX, UK.
3
Institute for Cell and Molecular Biosciences, Newcastle University, Framlington Place, Newcastle upon Tyne NE2 4HH, UK.
4
The Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Richardson Road, Newcastle upon Tyne NE2 4AX, UK. Electronic address: w.vollmer@ncl.ac.uk.
5
University Grenoble Alpes, Institut de Biologie Structurale, F-38027 Grenoble, France; CEA, DSV, Institut de Biologie Structurale, F-38027 Grenoble, France; CNRS, Institut de Biologie Structurale, F-38027 Grenoble, France. Electronic address: jean-pierre.simorre@ibs.fr.

Abstract

The bacterial cell envelope contains the stress-bearing peptidoglycan layer, which is enlarged during cell growth and division by membrane-anchored synthases guided by cytoskeletal elements. In Escherichia coli, the major peptidoglycan synthase PBP1A requires stimulation by the outer-membrane-anchored lipoprotein LpoA. Whereas the C-terminal domain of LpoA interacts with PBP1A to stimulate its peptide crosslinking activity, little is known about the role of the N-terminal domain. Herein we report its NMR structure, which adopts an all-α-helical fold comprising a series of helix-turn-helix tetratricopeptide-repeat (TPR)-like motifs. NMR spectroscopy of full-length LpoA revealed two extended flexible regions in the C-terminal domain and limited, if any, flexibility between the N- and C-terminal domains. Analytical ultracentrifugation and small-angle X-ray scattering results are consistent with LpoA adopting an elongated shape, with dimensions sufficient to span from the outer membrane through the periplasm to interact with the peptidoglycan synthase PBP1A.

PMID:
24954617
PMCID:
PMC4111904
DOI:
10.1016/j.str.2014.04.017
[Indexed for MEDLINE]
Free PMC Article

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