A small cellulose-binding-domain protein (cbd1) in phytophthora is highly variable in the non-binding amino terminus

Authors: Jones, Richard; Perez, Frances

Submitted to: Current Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/19/2017
Publication Date: 7/26/2017
Citation: Jones, R.W., Perez, F.G. 2017. A small cellulose-binding-domain protein (cbd1) in phytophthora is highly variable in the non-binding amino terminus. Current Microbiology. 74:1287-1293. https://doi.org/10.1007/s00284-017-1315-x.
DOI: https://doi.org/10.1007/s00284-017-1315-x

Interpretive Summary: An individual microbe that causes plant diseases can undergo changes that make detection difficult. Finding these changes can allow for new, improved methods of detection. We identified a gene that is the same within closely related members of a microbe, but differ between more distant relatives. This information was used to detect the microbe and distinguish between more distant microbe relatives. This information will be useful to scientists in identifying and tracking plant disease causing microbes.

Technical Abstract: The small cellulose binding domain protein CBD1 is tightly bound to the cellulosic cell wall of the plant pathogenic stramenophile Phytophthora infestans. Transgene expression of the protein in plants has also demonstrated binding to plant cell walls. A study was undertaken using 47 isolates of P. infestans from a worldwide collection, along with 17 other Phytophthora species and a related pathogen Plasmophora halstedii, to determine if the critical cell wall protein is subject to amino acid variability . Within the amino acid sequence of the secreted portion of CBD 1 encoded by the P. infestans isolates, 30 were identical with each other, and with P. mirabilis. Four isolates had one amino acid substitution, each in a different location, while one isolate had two amino acid substitutions. The remaining thirteen had five amino acid changes that were each in identical locations (D17/G, D31/G, I32/S, T43/A and G50/A), suggesting a single origin. Comparison of P. infestans CBD1 with CBD1 in 16 other Phytophthora species identified extensive amino acid variation among the 60 amino acids at the amino terminus of the protein, yet a high level of conservation from G61, where the critical cellulose binding domain sequences begins, to the end of the protein ( L110). Therefore while the region needed to bind to cellulose is conserved, the region that is available to interact with other cell wall components is subject to considerable variation. Application of this information allowed for the design of species-specific primers for PCR detection of P. infestans and P. sojae, by combining primers from the highly conserved and variable regions of the CBD1 gene.