Sheng WANG#, Fu-Di ZHONG#, Yong-Jiang ZHANG, Zu-Jian WU, Qi-Ying LIN, and Lian-Hui XIE*
( Key Laboratory of Pesticide and Biochemistry,Ministry of Education, Institute of Plant Virology,
Fujian Agriculture and Forestry University, Fuzhou 350002, China )

Abstract A new lectin, named UPL1, was purified from a green alga Ulva pertusa by an affinity chromatography on the bovine-thyroglobulin-Sepharose 4B column. The molecular mass of the algal lectin was about 23 kD by SDS-PAGE, and it specifically agglutinated rabbit erythrocytes. The hemagglutinating activity for rabbit erythrocytes could be inhibited by bovine thyroglobulin and N-acetyl-D-glucosamine. The lectin UPL1 required divalent cations for maintenance of its biological activity, and was heat-stable, and had higher activity within pH 6-8. The N-terminal amino acid sequence of the purified lectin was determined (P83209) and a set of degenerate primers were designed. The full-length cDNA of the lectin was cloned by rapid amplification of cDNA ends (RACE) method (AY433960). Sequence analysis of upl1 indicated it was 1084 bp long, and encoded a premature protein of 203 amino acids. The N-terminal sequence of the mature UPL1 polypeptide started at amino acid 54 of the deduced sequence from the cDNA, indicating 53 amino acids lost due to posttranslational modification. The primary structure of the Ulva pertusa lectin did not show amino acid sequence similarity with known plant and animal lectins. Hence, this protein may be the paradigm of a novel lectin family.

Key words Ulva pertusa; lectin; purification; cloning

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Received: October 21, 2003 Accepted: December 2, 2003
This work was supported by a grant from the Local Key Project of China in Fujian Province (2000H004)
# Who contributed equally to this article
*Corresponding author: Tel, 86-591-3769704; Fax, 86-591-3769704; E-mail, xielh@fjau.edu.cn