Waffenschmidt S, Woessner J P, Beer K, Goodenough U W
Institut für Biochemie, Universität zu Köln, Germany.
Plant Cell. 1993 Jul;5(7):809-20. doi: 10.1105/tpc.5.7.809.
Enzymatic removal of the cell wall induces vegetative Chlamydomonas reinhardtii cells to transcribe wall genes and synthesize new hydroxyproline-rich glycoproteins (HRGPs) related to the extensins found in higher plant cell walls. A cDNA expression library made from such induced cells was screened with antibodies to an oligopeptide containing the (SP)x repetitive domains found in Chlamydomonas wall proteins. One of the selected cDNAs encodes an (SP)x-rich polypeptide that also displays a repeated YGG motif. Ascorbate, a peroxidase inhibitor, and tyrosine derivatives were shown to inhibit insolubilization of both the vegetative and zygotic cell walls of Chlamydomonas, suggesting that oxidative cross-linking of tyrosines is occurring. Moreover, insolubilization of both walls was concomitant with a burst in H2O2 production and in extracellular peroxidase activity. Finally, both isodityrosine and dityrosine were found in hydrolysates of the insolubilized vegetative wall layer. We propose that the formation of tyrosine cross-links is essential to Chlamydomonas HRGP insolubilization.
酶法去除细胞壁可诱导莱茵衣藻营养细胞转录细胞壁基因，并合成与高等植物细胞壁中发现的伸展蛋白相关的富含羟脯氨酸的新糖蛋白（HRGPs）。用针对含有衣藻细胞壁蛋白中发现的(SP)x重复结构域的寡肽的抗体筛选由此类诱导细胞构建的cDNA表达文库。所选的一个cDNA编码一种富含(SP)x的多肽，该多肽还显示出重复的YGG基序。抗坏血酸（一种过氧化物酶抑制剂）和酪氨酸衍生物被证明可抑制衣藻营养细胞和合子细胞壁的不溶性化，这表明酪氨酸正在发生氧化交联。此外，两种细胞壁的不溶性化都伴随着H2O2产生和细胞外过氧化物酶活性的激增。最后，在不溶性营养细胞壁层的水解产物中发现了异二酪氨酸和二酪氨酸。我们认为酪氨酸交联的形成对于衣藻HRGP的不溶性化至关重要。
