title: Coating proteins: structure and cross-linking in fp-1 from the green shell mussel Perna canaliculus.
abstract: The protein family known as fp-1 provides mussel byssus with a protective outer coating and has drawn much attention for its water resistant bioadhesive properties in vitro. A new fp-l isolated from the green shell mussel Perna canaliculus (pcfp-1) reveals a composition dominated by only four amino acids: 3,4-dihydroxyphenyl-L-alanine (dopa), lysine, proline, and valine at approximately 20 mol % each. SDS-PAGE and MALDI-TOF mass spectrometry detected size variants at 48 and 52 kDa in preparations of purified Pcfp-1. The N-terminal sequence enabled construction of oligonucleotide primers for PCR and RACE-derived cDNAs from which the complete sequence of four variants was deduced. pcfp-1 deviates from all known homologues in other mussels in several notable respects: its mass is half, most of its sequence is represented by 75 tandem repeats of a tetrapeptide, i.e., PY*VK, in which Y* is dopa, prolines are not hydroxylated, and thiolate cysteines are clustered in homologous sequences at both the amino and carboxy termini. Amino acids in the repeat sequence show a striking resemblance to proline-rich cell wall proteins with tandemly repeated PPVYK pentapeptides [Hong, J. C., Nagao, R. T., and Key, J. L. (1987) J. Biol. Chem. 262, 8367-8376]. Cysteine plays a key role in cross-linking pcfp-1 by forming adducts with dopaquinone. Significant 5-S-cysteinyldopa and smaller amounts of 2-S-cysteinyldopa were detected in hydrolysates of the byssal threads of P. canaliculus. The cross-links could also be formed by oxidation of pcfp-1 in vitro using mushroom tyrosinase. Cysteinyldopa cross-links were present in trace amounts only in the byssus of other mussel species.
authors.affiliation: Molecular, Cellular and Developmental Biology Department and Marine Science Institute, University of California, Santa Barbara, California 93106, USA.
authors.forename: Hua
authors.initials: H
authors.lastname: Zhao
authors.forename: J Herbert
authors.initials: JH
authors.lastname: Waite
mesh_terms: D000268:Adhesiveness; D000595:Amino Acid Sequence; D000818:Animals; D049872:Bivalvia / Q000737:chemistry*; D016384:Consensus Sequence; D003548:Cysteinyldopa / Q000032:analysis; D007536:Isomerism; D008969:Molecular Sequence Data; D011506:Proteins / Q000737:chemistry* / Q000302:isolation & purification; D012091:Repetitive Sequences, Nucleic Acid; D021241:Spectrometry, Mass, Electrospray Ionization; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D011506:Proteins; D003548:Cysteinyldopa; C034513:2-S-cysteinyldopa