DESIGN OF CHIMERIC ANTI-MICROBIAL PROTEINS FOR RAPID CLEARANCE OF XYLELLA

• Author(s): Dandekar, Abhaya; Gupta, Nam; Hong-Geller, Elizabeth; McDonald, Karen; Bruening, George; Civerolo, Ed; Shiflett, Patrick; Unkefer, Cliff; Unkefer, Pat;
• Abstract: Xylella fastidiosa, a gram-negative xylem-limited bacterium is a causative agent of Pierces disease (PD) in California grapevines. During very early stages of Xylella fastidiosa (Xf) infection, specific proteins/carbohydrates/lipids on the outer membrane of Xf interact with plant cells and are important for virulence (Pieters, 2001). Design of a protein inhibitor that interrupts this step of the plant-Xf interaction will be useful in combating virulence and controlling PD. Traditionally, antibiotics are prescribed as a preferred therapy. Antibiotics target the enzymes involved in the biogenesis of the bacterial outer membrane and diminish pathogen viability. However, a pathogen often develops antibiotic resistance without the corresponding loss of virulence and pathogenicity (Baquero and Blazquez, 1997). In this UC/LANL project, we offer a novel countermeasure against Xf as a viable alternative to antibiotic therapy. We propose to develop chimeric anti-microbial proteins with two functional domains. One domain (referred hereafter as the surface recognition domain or SRD) will be designed to target either a protein or a carbohydrate moiety on the outer membrane whereas the other (a defensin molecule) will be designed to insert and lyse the Xf lipid membrane. For protein binding, the SRD will contain either an elastase or a single chain full-length variable region (scFv) antibody targeted against the newly discovered Xf outer membrane protein, mopB (Bruening et al., 2002). For carbohydrate binding, the SRD will contain the carbohydrate recognition domain (CRD) of a lectin (Barre et al, 2001; Feinberg et al., 2001; Sharma and Surolia, 1997) to specifically bind to the carbohydrate on the lipid head or on the Xylella surface. The defensin molecule will be chosen from group IV plant defensins that exhibit strong anti-bacterial activity (Segura et al., 1998).
• Publication Date: Aug 2003
• Journal: 2003 Pierce's Disease Research Symposium