BERTIN, M.J.*; POMPONI, S.A.; ELLINGTON, W.R.; Florida St. Univ., Tallahassee; HBOI, Fort Pierce, FL; Florida St. Univ., Tallahassee: Creatine and Arginine Kinases are Widespread in the Porifera

Creatine kinase (CK) and arginine kinase (AK) are expressed in cells that display high and variable rates of ATP turnover and belong to a highly conserved family of phosphoryl transferases called phosphagen kinases. Recently, mitochondrial (MtCK) and protoflagellar (protoflgCK) CK cDNAs from the demosponge Tethya aurantia have been cloned and sequenced (Sona et al., BBRC 317: 1207-1214 [2004]) and an AK cDNA from another demosponge Suberites domuncula has been cloned and sequenced (Perovic-Ottstadt et al., JEB 208: 737-646 [2005]). We have surveyed for the presence of CK and AK activities in two sponge classes by spectrophotometric enzyme assays of tissue extracts. Class Calcarea (three species) had AK activity only. Out of >30 members of Class Demospongae, a small number had CK activity only while roughly equal numbers had either AK activity only or both AK and CK activity. RTPCR of RNA from two of these demosponges showed that this CK activity consists of both Mt- and protoflgCKs. Total RNA was isolated from three hexactinellid (glass) sponges collected by submersible. RTPCR amplifications of these RNAs showed that all three express MtCK and protoflgCK; an AK was amplified from the RNA from one species. Hexactinellids appear to have diverged first in the sponge lineage followed by demosponges and then calcareans. Our results show that AK is widespread in all three sponge classes and that the two CK isoforms (Mt- and protoflg-) evolved prior to the divergence of the hextactinellids. The physiological role of both CK and AK in poriferans remains to be elucidated, although it seems likely that these reactions mitigate spatial ATP supply-demand mismatches in cells. (Supported by NSF grant IOB-0130024 to WRE)