Identification and Characterization of a Novel Biotin Biosynthesis Gene inSaccharomyces cerevisiae

Abstract

Yeast Saccharomyces cerevisiae cells generally cannot synthesize biotin, a vitamin required for many carboxylation reactions. Although sake yeasts, which are used for Japanese sake brewing, are classified as S. cerevisiae, they do not require biotin for their growth. In this study, we identified a novel open reading frame (ORF) in the genome of one strain of sake yeast that we speculated to be involved in biotin synthesis. Homologs of this gene are widely distributed in the genomes of sake yeasts. However, they are not found in many laboratory strains and strains used for wine making and beer brewing. This ORF was named BIO6 because it has 52% identity with BIO3, a biotin biosynthesis gene of a laboratory strain. Further research showed that yeasts without the BIO6 gene are auxotrophic for biotin, whereas yeasts holding the BIO6 gene are prototrophic for biotin. The BIO6 gene was disrupted in strain A364A, which is a laboratory strain with one copy of the BIO6 gene. Although strain A364A is prototrophic for biotin, a BIO6 disrupted mutant was found to be auxotrophic for biotin. The BIO6 disruptant was able to grow in biotin-deficient medium supplemented with 7-keto-8-amino-pelargonic acid (KAPA), while the bio3 disruptant was not able to grow in this medium. These results suggest that Bio6p acts in an unknown step of biotin synthesis before KAPA synthesis. Furthermore, we demonstrated that expression of the BIO6 gene, like that of other biotin synthesis genes, was upregulated by depletion of biotin. We conclude that the BIO6 gene is a novel biotin biosynthesis gene of S. cerevisiae.

Discovery of a SAR11 growth requirement for thiamin’s pyrimidine precursor and its distribution in the Sargasso Sea

“…P. ubique, implying consumption of the nutrient (Table 2). Previously, background levels of vitamins in heterotrophic growth medium were proposed to underlie scant growth of vitamin auxotrophs in the absence of added vitamins (Norman et al, 1981;Wu et al, 2005), and the difficulty associated with thiamin removal from growth medium has been noted (Button, 1968). The number of HMP molecules required per Ca.…”

Genomic Insights into the Saccharomyces sensu stricto Complex

“…While the majority of S. cerevisiae isolates, including those used in winemaking and brewing, are biotin auxotrophs, some, such as those used for the production of sake, are able to synthesize biotin de novo, presumably due to the very low biotin content of sake mash (Wu et al 2005). This conversion to biotin prototrophy is due to the reacquisition of two ORFs, BIO1 and BIO6, that encode the enzymatic steps that are missing in the biotin pathway of most other strains (Wu et al 2005;Hall and Dietrich 2007).…”

“…While the majority of S. cerevisiae isolates, including those used in winemaking and brewing, are biotin auxotrophs, some, such as those used for the production of sake, are able to synthesize biotin de novo, presumably due to the very low biotin content of sake mash (Wu et al 2005). This conversion to biotin prototrophy is due to the reacquisition of two ORFs, BIO1 and BIO6, that encode the enzymatic steps that are missing in the biotin pathway of most other strains (Wu et al 2005;Hall and Dietrich 2007). As for many of these species-specific ORFs, the donor species of these DNA sequences is also not clear; however, suggestions hint at a de novo origin in S. cerevisiae, rather than horizontal acquisition, through duplication and neofunctionalization of BIO3 (BIO6) and YJR154W (BIO1) (Hall and Dietrich 2007).…”

The Reacquisition of Biotin Prototrophy in Saccharomyces cerevisiae Involved Horizontal Gene Transfer, Gene Duplication and Gene Clustering

“…(Shchelokova and Vorob'eva 1982) are capable of synthesizing biotin, and some such as Ashbya gossypii (Dietrich et al 2004) lack the genes necessary to synthesize biotin. Some fungal species that are incapable of synthesizing biotin still have portions of the biotin biosynthetic pathway and are capable of utilizing intermediates to synthesize biotin (Phalip et al 1999;Wu et al 2005). In S. cerevisiae, many wild isolates cannot synthesize biotin but nevertheless retain the BIO2, BIO3, and BIO4 genes from this biosynthetic pathway.…”

“…Most of what is known about biotin biosynthesis in eukaryotes is derived from work in Arabidopsis thaliana and S. cerevisiae (Zhang et al 1994;Phalip et al 1999;Streit and Entcheva 2003;Pinon et al 2005;Wu et al 2005). In S. cerevisiae, three of the genes involved in biotin synthesis and intermediate transport are found within a subtelomeric cluster located on chromosome XIV (BIO3, BIO4, and BIO5) (Phalip et al 1999).…”