Complementation of a yeast coq10 null mutant by expression of C. crescentus CC1736 requires the amino acid residue V70 for respiratory function. Wild-type, respiratory deficient cor1, yeast Q-less coq3 null mutant, and the coq10 null mutant were grown in SD complete medium and harvested during mid-log phase (0.2-1.0 OD600nm). The coq10 null mutant W303ΔCOQ10 was transformed with each of the following multi-copy plasmids: Empty (pRS426), COQ8 (p4HN4), COQ10 (pG140/ST3), CC1736 (pRCM-CC1736), or with plasmids encoding CC1736 with amino acid substitutions K115E (pRCM-K115E) or V70K (pRCM-V70K). Yeast transformants were grown in selective media and harvested during mid-log phase. Cells were washed twice with sterile water and diluted to a final OD600nm of 0.2. Serial dilutions (1:5) were prepared and 2 μl of each sample was spotted onto SD-Complete or SD-Ura, and rich glycerol (YPG) plate medium and incubated at 30 °C for 3 or 4 days, as indicated.