COMPARATIVE STUDY OF XYLELLA FASTIDIOSA SURFACE PROTEINS EXHIBITING HIGH CONTENTS CYSTEINE RESIDUES: IMPACT IN PATHOGENICITY

• Author(s): Andersen, Peter; Ishida, Maria Lucia; Leite, Breno;
• Abstract: The Calcium Bridging Hypothesis (CBH) validity is highly dependent on the existence of thiol moieties on the surface of Xylella fastidiosa (Xf) cells. The major question that remains to be addressed is how surface thiol and divalent ions would mediate aggregation. Strong evidence was revealed form studies with the Cowpea Mosaic Virus (CMV), by the Scripps Research Institute, California. Dissimilar patterns of surface cysteine on the surface of CMV particles resulted in distinct attachment properties. Likewise, cell-cell and cell-xylem interactions may also be mediated by the establishment of ionic bonds involving Ca(++), and Mg(++). Cysteine residues located on the outer membrane region of Xf surface proteins can form covalent disulfide linkages with thiol residues from other cells. Calcium and magnesium ions could also bridge negatively charged surface areas. Our objective in the present work was to search for potential surface proteins with thiols (negative charge) on the Xf cell surface. Several adhesion related proteins were investigated. We especially targeted domains localized outside the cell, and focused on the extracellular cysteine-rich residues regions. Hemagglutinin-like proteins presented the desired characteristics to fit the hypothesis. Other surface proteins are discussed, including type IV fimbriae, recently demonstrated to be involved in Xf twitching.
• Publication Date: Dec 2005
• Journal: 2005 Pierce's Disease Research Symposium