Recent insights into microbial physiology

Application of zwitterionic detergent to the solubilization of Klebsiella pneumoniae outer membrane proteins for two-dimensional gel electrophoresis

Klebsiella pneumoniae is a frequent cause of nosocomial respiratory, urinary and gastrointestinal tract infections and septicemia with the multidrug-resistant K. pneumoniae being a major public health concern. Outer membrane proteins (OMPs) are important virulence factors responsible for the appropriate adaptation to the host environment. They constitute of the antigens being the first in contact with infected organism. However, K. pneumoniae strains are heavily capsulated and it is important to establish the OMPs isolation procedure prior to proteomics extensive studies. In this study we used Zwittergent Z 3-14® as a detergent to isolate the OMPs from K. pneumoniae cells and resolve them using two-dimensional electrophoresis (2-DE). As a result we identified 134 protein spots. The OMPs identified in this study are possible candidates for the development of a protein-based vaccine against K. pneumoniae infections.

Robin James Rowbury: 30th April 1937 – 11th July 2012

Robin Rowbury, Life Sciences Editor of Science Progress since 1995, died in July 2012 following a long battle with cancer. Despite his illness he continued working right up until May this year both writing and promoting the journal wherever he could. In this issue, we are proud to feature his final article in which he describes the multi-talented character who was Robert Hooke. However, first we are publishing some tributes to Robin whom we remember in the office as a gentle man with a very dry sense of humour, as well as a hard-working author and editor. We shall all certainly miss him.

Professor David Phillips CBE, FRSC who worked as Physical Sciences Editor alongside Robin describes him as a real gentleman and an excellent academic.

Dr David Smith, his lifelong colleague from University College London remembers Robin as a supportive friend and colleague, a great teacher, and a gifted research scientist. He influenced many lives, and numerous students owe their successful careers to his guidance.

These sentiment are reflected in three more tributes from former colleagues.

Two-dimensional gel electrophoresis in bacterial proteomics

Two-dimensional gel electrophoresis (2-DE) is a gel-based technique widely used for analyzing the protein composition of biological samples. It is capable of resolving complex mixtures containing more than a thousand protein components into individual protein spots through the coupling of two orthogonal biophysical separation techniques: isoelectric focusing (first dimension) and polyacrylamide gel electrophoresis (second dimension). 2-DE is ideally suited for analyzing the entire expressed protein complement of a bacterial cell: its proteome. Its relative simplicity and good reproducibility have led to 2-DE being widely used for exploring proteomics within a wide range of environmental and medically-relevant bacteria. Here we give a broad overview of the basic principles and historical development of gel-based proteomics, and how this powerful approach can be applied for studying bacterial biology and physiology. We highlight specific 2-DE applications that can be used to analyze when, where and how much proteins are expressed. The links between proteomics, genomics and mass spectrometry are discussed. We explore how proteomics involving tandem mass spectrometry can be used to analyze (post-translational) protein modifications or to identify proteins of unknown origin by de novo peptide sequencing. The use of proteome fractionation techniques and non-gel-based proteomic approaches are also discussed. We highlight how the analysis of proteins secreted by bacterial cells (secretomes or exoproteomes) can be used to study infection processes or the immune response. This review is aimed at non-specialists who wish to gain a concise, comprehensive and contemporary overview of the nature and applications of bacterial proteomics.