Putative RuBisCO Activase cfxQ in the Toxic Alga Heterosigma akashiwo

Putative RuBisCO Activase cfxQ in the Toxic Alga Heterosigma akashiwo
Amanda S. Hoyt and Kun-Lin Lee, Presenters
Rose Ann Cattolico, Research Advisor

CO2 entrance in the Calvin Cycle of many autotrophic organisms is driven by the enzyme Rubulose 1,5-Bisphosphate Carboxylase/Oxygenase (RuBisCO). Analysis of the chloroplast-encoded cfxQ in the Raphidophyte Heterosigma akashiwo shows sequence homology to bacterial RuBisCO Activases and that it is evolving extremely rapidly. Though present in almost 2,500 copies per cell, the presence of single nucleotide polymorphisms (SNPs) has been documented to occur when geographically distinct algal populations were analyzed. Five variants of the cfxQ gene have been identified among fifteen Heterosigma strains sequenced, and the nucleotide changes have been observed to result in both synonymous and non-synonymous amino acid alterations in the resulting proteins. Preliminary modeling studies of the cfxQ protein have shown non-random clustering of amino acid changes, suggesting selection for localized mutations, possibly indicating an important functional domain. We hypothesize that cfxQ is a RuBisCO Activase and the SNPs observed may impact its function. The goals of this study are to (i) complete SNP analysis of the cfxQ sequence in six additional Heterosigma strains using PCR and sequencing methods, (ii) overexpress cfxQ variants with the RuBisCO operon to examining the SNPs' effect on their interactions, (iii) explore the functionality of cfxQ by assaying for Activase activity, and (iv) study the relationship between the transcriptional levels of cfxQ and RuBisCO using quantitative PCR.