Putative multiadhesive protein from the marine spongeGeodia cydonium: Cloning of the cDNA encoding a fibronectin-, an SRCR-, and a complement control protein module†

Abstract

Sponges (Porifera) representing the simplest metazoan phylum so far have been thought to possess no basal lamina tissue structures. One major extracellular matrix protein that is also a constitutive glycoprotein of the basal lamina is fibronectin. It was the aim of the present study to identify the native protein from the marine sponge Geodia cydonium and to isolate the corresponding cDNA. In crude extracts from this sponge protein(s) of Mr of Ý230 and Ý210 kDa could be visualized by Western blotting using an anti‐fibronectin [human] antibody. By PCR cloning from a cDNA library of G. cydonium we isolated a cDNA comprising one element of fibronectin, the type‐III (FN3) module. The cDNA (2.3 kb long), encoding a 701 amino acid [aa] long putative “multiadhesive protein” termed MAP―GEOCY, was found to contain (i) a fibronectin‐, (ii) a scavenger receptor cysteine‐rich [SRCR]‐, and (iii) a short consensus repeat [SCR] module. The 89 aa long fibronectin module comprises the characteristic topology and conserved aa found in fibronectin type‐III (FN3) elements. The SRCR module (101 aa) features the characteristics of group B SRCR molecules. The predominant proteins belonging to this group are the mammalian WC1‐, M130‐, CD6‐ and CD5 antigens that probably are involved in immunological reactions. The SCR module (54 aa) shows the characteristics of type III SCR modules found in complement receptors. Phylogenetic analyses performed with all three building blocks of the “multiadhesive protein” showed that the respective sponge modules form independent, possibly basal, lineages in trees that include the corresponding modules from higher metazoan animals. In summary, these data demonstrate for the first time that the phylogenetically oldest Metazoa, the sponges, contain protein modules seen in higher animals in proteins of the extracellular matrix and in molecules involved in cell‐mediated immune reactions in vertebrates. J. Exp. Zool. 282:332–343, 1998. © 1998 Wiley‐Liss, Inc.

Ethylene Modulates Gene Expression in Cells of the Marine SpongeSuberites domuncula and Reduces the Degree of Apoptosis

“…The deduced polypeptide comprises three autophosphorylation sites at Thr-283, Thr-302, and Ser-311, the autoinhibitory region (aa 269 and aa 299 ), which partially overlaps with the calmodulin-binding domain (aa 288 and aa 307 ) and the variable region, which spans in S. domuncula the region aa 311 to aa 370 (24). The Ϸ20 aa at the COOH terminus, which are present in the ␦-subunits of other CaM kinase II, are missing in the sponge sequence, whereas the Ser/Thr protein kinase active site (aa 129 and aa 141 ) and the ATP-binding signature (aa 17 and aa 25 ) are found as indicated in Fig. 7A.…”

“…Recently, a technique was established that allows single sponge cells to associate to "organ-like" aggregates, termed primmorphs; in this state the cells are able to divide (16). Evidence has been presented that some cells within the primmorphs undergo apoptotic death; subsequently the resulting cell fragments are very likely taken up via phagocytosis by those cells that express on their surface receptors composed of scavenger receptor cysteine-rich repeats (7,17). So far, the volatile products in the marine environment including ethylene have not been experimentally studied as a potential energy source for sponges.…”

The scavenging capacity of DMBT1 is impaired by germline deletions

“…The Scavenger Receptor Cysteine-Rich (SRCR) proteins are an archaic group of highly conserved proteins in animals (Aruffo et al 1997; Freeman et al 1990; Muller et al 1999; Pahler et al 1998; Resnick et al 1994). The SRCR-superfamily is comprised of cell membrane-anchored proteins as well as secretory proteins.…”

Emergence and Disappearance of an Immune Molecule, an Antimicrobial Lectin, in Basal Metazoa

“…An early illustration and functional analysis of phagocytosis in sponges were given by Metchnikoff (8). Molecular data indicate that receptors present on the cell surface might have the capacity to discriminate between self-self and non-self (6); examples are receptors that comprise both SRCR (scavenger receptor comprising cysteine-rich) group A domains (9) and/or SRCR group B domains (10). In addition, sponges are very rich in lysosomal enzymes, e.g.…”