Identification and molecular characterization of the Arabidopsis homolog to the Saccharomyces cerevisiae BIO5 gene

Here we describe the identification and characterization of the Arabidopsis homolog (At2g01170.1) to the S. cerevisiae BIO5 transporter of the biotin precursor 7-keto 8-aminopelargonic acid (KAPA). The Arabidopsis protein encoded by At2g01170 (also called BAT1) shares 22.1% identity and 36.8% similarity to the S. cerevisiae BIO5 protein, and the two proteins have highly conserved computationally predicted secondary structures, with both proteins predicted to have 12 α-helical trans-membrane domains. The Arabidopsis BIO5 homolog was also able to complement S. cerevisiae bio5 mutants. Arabidopsis At2g01170 (bio5) mutants did not have the growth phenotype observed in S. cerevisiae bio5 mutants though there was an impact on the biotin content associated with the mutant. The previously unknown subcellular location of BIO5 was determined to be in the plasma membrane by a GFP tagging study. This Arabidopsis BIO5 homolog is proposed to facilitate the distribution of biotin or its precursors, such as KAPA among the plant\u27s cells and tissues