S-layer mediated display of customized glycans enabled by glycosylation engineering - Novel opportunities for biostimulation and biotargeting.
Abstract
Glycans are critical components in many biological processes. Cells use them to communicate with each other, bacteria and viruses use them to infect their hosts, and cancer cells use them to chart new territory in the body. Frequently, carbohydrate-mediated phenomena fall in the categories of biostimu¬lation and biotargeting, with the carbohydrates in many cases being coupled to a protein. Thus, glycosylation engineering to obtain customized protein glycosylation will decisively increase our capabilities in influencing and controlling complex biological systems. Bacteria are regarded promi¬sing candidates for this endeavor, because they are easily tractable, have favorable process economics to produce glycoproteins, and, most importantly, according to recent data, there are effective ways to make homogeneously glycosylated proteins in bioengineered bacteria. Despite of the power of bacterial cell surface display for protein display in basic and applied research, this strategy has not yet been exploited for customized carbohydrates. In the present project, we propose to undertake a biomimetic approach, in which bacterial protein glycosylation engineering shall be combined with multivalent surface display of customized glycans by using the naturally glycosylated bacterial cell surface layer protein of the Gram-positive bacterium Paenibacillus alvei CCM 2051T as a 2D crystalline, nanometer-scale display matrix. This matrix is generated through self-assembly, with the attached glycan chains being naturally orientated towards the ambient environment. We hypothesize that due to the similarities between the S layer protein glycosylation pathway and other bacterial polysaccharide biosynthesis systems, engineering of customized S layer glyco¬protein glycans will be possible. As a way to analyze the basis for S layer glycosylation engineering and to test our hypothesis, our research goals are: A) Investigation of the native tyrosine O glycosyla¬tion sites on the S layer protein; B) Unraveling mechanisms for glycan chain length regulation, export and oligosaccharide:protein transfer; C) Engineering S layer protein SpaA glycosylation in selected glycosylation mutants of Pa with diverse heterologous saccharides to demonstrate the convergence of the S-layer glycosylation machinery with foreign bacterial glycosylation systems; D) Extension of the glycosylation potential of the S layer protein SpaA by exchanging the native O glycosylation site(s) by bacterial N glycosylation site(s) that are recognized by the cognate glycosylation machineries. This system shall allow ultimate control over the position, quantity and type of carbohydrate structure present on the bacterium. It provides a unique framework for studying the biostimulation and biotargeting behavior of various carbohydrates of interest in a setting that mirrors the natural dynamic behavior of a cell and may help to enhance the affinity and specificity of interaction between carbo¬hydrates and their ligands through multivalent presentation. The present project follows the current trend of exploiting means for organizing biological functions at the nanometer level aiming at the development of novel concepts for life and non-life sciences. It provides an innovative approach to advance the opportunities emanating from glycobiology for the fields of human health and biomaterial design.
keywords S-layer glycoprotein self-assembly protein glycosylation engineering cell surface display nanostructured biomaterial
Publikationen
Project staff
Christina Schäffer
Univ.Prof. Dipl.-Ing. Dr.nat.techn. Christina Schäffer
christina.schaeffer@boku.ac.at
Tel: +43 1 47654-80203
BOKU Project Leader
01.04.2010 - 31.03.2015
Paul Messner
Ao.Univ.Prof.i.R. Dipl.-Ing. Dr.nat.techn. Paul Messner
paul.messner@boku.ac.at
Project Staff
01.04.2010 - 31.03.2015
BOKU partners
External partners
National Research Council of Canada, Institute for Biological Sciences
none
partner
University of Alberta
Prof. Mario Feldman
partner