Ikeuchi M, Eggers B, Shen G Z, Webber A, Yu J J, Hirano A, Inoue Y, Vermaas W
Institute of Physical and Chemical Research (RIKEN), Solar Energy Research Group, Saitama, Japan.
J Biol Chem. 1991 Jun 15;266(17):11111-5.
We cloned and sequenced the psbK gene, coding for a small photosystem II component (PSII-K), from the transformable cyanobacterium, Synechocystis sp. PCC 6803, and determined the N-terminal sequence of mature PSII-K. The psbK gene product is processed by cleaving off eight amino acid residues from the N terminus. A mutant lacking psbK was constructed; this mutant grew photoautotrophically, but its growth rate was reduced. The number of photosystem II reaction centers on a chlorophyll basis was decreased by less than a factor of 2 in the psbK-deletion mutant. In Synechocystis sp. PCC 6803, the psbK gene is transcribed as a single gene and is not part of an operon. Single-site mutations were introduced into psbK leading to early termination or deletion of the presequence. The phenotype of these mutants strongly resembles that of the psbK deletion mutant, indicating that indeed the change in phenotype in the deletion mutant is directly correlated with PSII-K. PSII-K is not essential for photosystem II assembly or activity but is needed for optimal photosystem II function.
我们从可转化的蓝藻集胞藻PCC 6803中克隆并测序了编码小型光系统II组分（PSII-K）的psbK基因，并确定了成熟PSII-K的N端序列。psbK基因产物通过从N端切除八个氨基酸残基进行加工。构建了一个缺失psbK的突变体；该突变体能够进行光合自养生长，但其生长速率降低。基于叶绿素的光系统II反应中心数量在psbK缺失突变体中减少不到2倍。在集胞藻PCC 6803中，psbK基因作为单个基因转录，不属于操纵子的一部分。将单点突变引入psbK导致前序列提前终止或缺失。这些突变体的表型与psbK缺失突变体非常相似，表明缺失突变体中的表型变化确实与PSII-K直接相关。PSII-K对于光系统II的组装或活性不是必需的，但对于光系统II的最佳功能是必需的。
