CHARACTERIZATION OF A CDNA-ENCODING A CYTOSOLIC PEPTIDYLPROLYL CIS-TRANS-ISOMERASE FROM BLATTELLA-GERMANICA

Cyclophilins are an abundant and ubiquitous class of proteins first id entified by their high affinity for the immunosuppressive drug cyclosp orin A. Cyclophilins have peptidylprolyl cis/trans-isomerase activity in vitro, and thus may be involved in protein folding and trafficking in vivo. In this study, we report the cloning and characterization of a Blattella germanica cyclophilin cDNA. Analysis of this 846-bp cDNA r eveals an open reading frame coding for a polypeptide of 164 amino aci d residues with a molecular mass of 17934 Da. This B. germanica cyclop hilin shares a central peptidylprolyl cis/trans-isomerase and a cyclos porin-A-binding domain with other cyclophilin sequences. The B. german ica cyclophilin amino acid sequence shares 83% identity with the cytos olic cyclophilin isoform from Drosophila melanogaster (Cyp-1). This id entity suggests that B. germanica cyclophilin is a member of the cytos olic cyclophilin A (CyPA) family. From the alignment of cyclophilin se quences, we have found that 62 residues (positional identity of 40%) h ave remained invariant in eukaryotes for more than 1 billion years of divergence. We calculated a unit evolutionary period of 30.9 million y ears for the cytosolic isoform. Northern-blot analyses show that B. ge rmanica CyPA mRNA is abundant, and present in all insect organs tested . The highest values for B. germanica cyclophilin mRNA tissue content were found in 6-day-old ovary, followed by brain, testis, and gut (15- 30% the content of ovary). The muscle, fat body, and colleterial gland contained the lowest cyclophilin mRNA level (1-5% the content of ovar y). There is a developmental pattern of gene expression affecting the embryo stages. These results suggest that this ubiquitously expressed B. germanica cyclophilin is subject to a differential regulation in ti ssues and during development. Southern-blot analysis of B. germanica D NA shows that only one copy of the CyPA gene is present per genome, wh ereas at least 20 genes or pseudogenes were detected in the mammalian genome.