High impact information on CYB2

• The internal deletion of the seven repeated amino acid sequences containing the KCPVDH motif in the CYP1(HAP1) protein modifies the heme responsiveness phenomenon observed in vitro in the band-shift experiments and in vivo in the transcription of the CYB2, CYC1, CYP3(CYC7) and ERG11 genes [1].
• The yeast CYB2 gene encodes an L-lactate:cytochrome c oxidoreductase that oxidizes lactate, donates electrons directly into the mitochondrial respiratory chain, and supports lactate-dependent respiration [2].
• Furthermore, we have shown that the CYB2 promoter contains one cis negative regulatory region and two heme-dependent positive regions, one of which is controlled by the transcriptional regulator CYP1 (HAP1) which is involved in the modulation of the expression of several oxygen-regulated genes [3].
• These studies indicated that regulation of the CYB2 gene is subject to several metabolic controls at the transcriptional level: inhibition due to glucose fermentation, induction by lactate, and inhibition in anaerobiosis or in absence of heme biosynthesis [3].
• In this study, we show that Hap1p is the main transcriptional activator involved in the control of CYB2 transcription [4].

Biological context of CYB2

• Selection for mutants which release glucose repression of the CYB2 gene was used to identify genes which regulate repression of mitochondrial biogenesis [5].
• We found that Hap1p activity, known to be oxygen dependent, is effected by DNA-protein interaction with two binding sites present in the CYB2 promoter [4].
• Transformation of the mutant with a K. lactis genomic library allowed the isolation of the KlCYB2 gene, restoring the growth on lactate and the L-LCR activity [6].

Associations of CYB2 with chemical compounds

• The DLD gene was cloned by complementation for growth on D-, L-lactate in the strain WWF18-3D, carrying both a CYB2 disruption and the dld mutation [7].
• These results are discussed together with the role of L-LCR and D-LCR in lactate metabolism of S. cerevisiae [7].
• We selected several lactate- pyruvate+ mutants in a cyb2 genetic background [7].

Other interactions of CYB2

• Finally, our results suggest that the Adr1p transcriptional activator is also required in CYB2 transcription control [4].

References