Faculty Collaboration Database

Concentration-dependent oligomerization and oligomeric arrangement of LptA. Protein Sci 2012 Feb;21(2):211-8

Date

11/24/2011

Pubmed ID

22109962

Pubmed Central ID

PMC3324765

DOI

10.1002/pro.2004

Scopus ID

2-s2.0-84856173418 (requires institutional sign-in at Scopus site)   55 Citations

Abstract

Gram-negative bacteria such as Escherichia coli have an inner membrane and an asymmetric outer membrane (OM) that together protect the cytoplasm and act as a highly selective permeability barrier. Lipopolysaccharide (LPS) is the major component of the outer leaflet of the OM and is essential for the survival of nearly all Gram-negative bacteria. Recent advances in understanding the proteins involved in the transport of LPS across the periplasm and into the outer leaflet of the OM include the identification of seven proteins suggested to comprise the LPS transport (Lpt) system. Crystal structures of the periplasmic Lpt protein LptA have recently been reported and show that LptA forms oligomers in either an end-to-end arrangement or a side-by-side dimer. It is not known if LptA oligomers bridge the periplasm to form a large, connected protein complex or if monomeric LptA acts as a periplasmic shuttle to transport LPS across the periplasm. Therefore, the studies presented here focus specifically on the LptA protein and its oligomeric arrangement and concentration dependence in solution using experimental data from several biophysical approaches, including laser light scattering, crosslinking, and double electron electron resonance spectroscopy. The results of these complementary techniques clearly show that LptA readily associates into stable, end-to-end, rod-shaped oligomers even at relatively low local protein concentrations and that LptA forms a continuous array of higher order oligomeric end-to-end structures as a function of increasing protein concentration.

Author List

Merten JA, Schultz KM, Klug CS

Authors

Candice S. Klug PhD Professor in the Biophysics department at Medical College of Wisconsin
Kathryn M. Schultz Research Scientist I in the Biophysics department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Carrier Proteins
Cross-Linking Reagents
Dose-Response Relationship, Drug
Escherichia coli Proteins
Models, Biological
Models, Molecular
Multiprotein Complexes
Osmolar Concentration
Protein Folding
Protein Multimerization
Protein Structure, Quaternary