The dynamic nature of bacterial surfaces: Implications for metal–membrane interaction

Abstract

Bacterial envelopes are chemically complex, diverse structures. Chemical and physical influences from cellular microenvironments force lipids, proteins, and sugars to organize dynamically. This constant reorganization serves to maintain compartmentalization and function, but also affects the influence of charged functional groups that drive electrochemical interactions with metal ions. The interactions of metal species with cell walls are of particular interest because (i) metals must be taken up or excluded to maintain cell function, and (ii) electrochemical interactions between charged metals and anionic ligands are inevitable. In this review we explore the associations of metals with metal-reactive ligands found within bacterial envelopes, and outward to include those within biofilm matrics. The mechanisms that underpin metal binding to these ligands have not been well considered with respect to the dynamic organization of the biological structures themselves. Bacteria respond sensitively and rapidly to growth environment with de novo syntheses of chemical constituents, which can impact metal interactions. We discuss causes of membrane chemical variability as observed in laboratory experiments, and offer consequences for this adaptability in natural settings. The structural impacts of metal ion associations with bacterial envelopes are often overlooked. This review explores how dynamic bacterial surface chemistry influences metal binding and, in turn, how metal ions impact membrane organization in laboratory and natural conditions.

Keywords::

• Bacterial membranes
• membrane chemistry
• metals
• complexation chemistry
• biofilms

Acknowledgements

We wish to thank Dianne Moyles (University of Guelph) for transmission electron microscopy advice and assistance, as well as Dr. Helmut Heller (Leibniz-Rechenzentrum, LRZ) for his kindly provided coordinate sets for phospholipid membranes in various phase states. Thanks are also given to Sirine Fakra (Lawrence Berkeley National Laboratory, Berkeley CA, USA) for STXM maps, and Glynis Perret (University of Guelph) for discussions and advice on spectroscopy techniques. We also thank Dr. Susan Koval (University of Western Ontario), Dr. Jack Trevors (University of Guelph), and Dr. John Dutcher (University of Guelph) for their valuable advice. The funding for this work was provided by a Discovery grant from the National Science and Engineering Research Council of Canada.

Declarations of interest

The authors report no declarations of interest.

Notice of Correction

The version of this article published online ahead of print on 27th July 2012 contained an error on page 8. Equation 4 SHOULD have read:

but it was initially published as:

The error has been corrected for this version.