The dynein gene family in Chlamydomonas reinhardtii

To correlate dynein heavy chain (Dhc) genes with flagellar mutations and gain insight into the function of specific dpnein isoforms, we placed eight members of the Dhe gene family on the genetic map of Chlamydomonas. Using a PCR-based strategy, we cloned 11 Dhe genes from Chlamydomonas. Comparisons with other Dhe genes indicate that two clones correspond to genes encoding the alpha and beta heavy chains of the outer dynein arm. Alignment of the predicted amino acid sequences spanning the nucleotide binding site indicates that the remaining nine clones can be subdivided into three groups that are likely to include representatives of the inner-arm Dhc isoforms. Gene-specific probes reveal that each clone represents a single-copy gene that is expressed as a transcript of the appropriate size (>13 kb) sufficient to encode a high molecular weight Dhc polypeptide. The expression of all nine genes is upregulated in response to deflagellation, suggesting a role in axoneme assembly or motility. Restriction fragment length polymorphisms between divergent C. reinhardtii strains have been used to place each Dhe gene on the genetic map of Chlamydomonas. These studies lay the groundwork for correlating defects in different Dhe genes with specific flagellar mutations.