Mitochondrial co-chaperone required for ubiquinol-cytochrome c oxidoreductase (mitochondrial respiratory chain complex III) activity. Interacts with QCR2. Induced by high temperature (at protein level). Decreases electron flow through the mitochondrial respiratory chain complex III (PubMed:32518190). Increases level of depolarized mitochondria (PubMed:32518190). Abnormal cell wall structure resulting in abnormal capsule attachment (PubMed:32518190). Sensitive to iron starvation (PubMed:32518190). Abolishes cell population growth on non-fermentable carbon sources (glycerol, lactate, and succinate) (PubMed:32518190). Decreases cell population growth (PubMed:32518190). Decreases virulence in a mouse intranasal model of infection (PubMed:32518190). Belongs to the DnaJ family. Truncated N-terminus.