PHYSICAL AND FUNCTIONAL REPETITION IN A BACTERIAL ICE NUCLEATION GENE
PHYSICAL AND FUNCTIONAL REPETITION IN A BACTERIAL ICE NUCLEATION GENE
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DOI：
10.1038/317645a0
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发表时间：
1985-01-01
期刊：
影响因子：
64.8
通讯作者：
WARREN, GJ
中科院分区：
文献类型：
--
作者：
GREEN, RL;WARREN, GJ
物理过程的成核与催化不同，作为蛋白质的功能，它是非常不寻常的。在过冷水中形成冰核的能力是欧文氏菌属、假单胞菌属和黄单胞菌属 1-3 某些细菌属成员的特性。这一特性与细菌对植物造成冻害的能力有关。 Orseret 等人 4 已经证明 DNA 的单个小区域编码这种表型，并且有证据表明磷脂酰肌醇参与其中 5。在某些耐冻昆虫的血淋巴中也发现了生物冰核。据认为，冰成核位点必须将水分子结合成类似于冰晶的有序阵列。我们现在已经确定了来自丁香假单胞菌的冰核基因的序列。它预测翻译产物的结构与模板的作用一致，包含共有八肽 Ala-Gly-Tyr-Gly-Ser-Thr-Leu-Thr 的 122 个不完美重复。所有重复都是连续的，并且高阶周期性始终叠加在八肽图案上。缺失分析表明，重复结构的大多数区域对于功能来说并不是必需的。最多可删除 68 个八肽而不消除冰成核，但所有删除均显示活性降低。这表明重复的肽单独对成核过程做出贡献，正如预期的那样，如果它们充当水结合阵列的单独单元的话。
Nucleation of a physical process is distinct from catalysis, and as the function of a protein it is highly unusual. The ability to nucleate ice formation in supercooled water is a property of some members of the bacterial generaErwinia, PseudomonasandXanthomonas1–3. This property is implicated in the ability of bacteria to cause frost injury to plants. Orseret al.4have demonstrated that a single small region of DNA encodes this phenotype, and there is evidence that phosphatidylinositol is involved5. Biological ice nuclei are also found in the haemolymph of certain freeze-tolerant insects6. It is thought that an ice nucleation site must bind water molecules in an orderly array resembling an ice crystal. We have now determined the sequence of an ice nucleation gene fromPseudomonas syringae. It predicts a translation product whose structure is consistent with the role of template, containing 122 imperfect repeats of the consensus octapeptide Ala-Gly-Tyr-Gly-Ser-Thr-Leu-Thr. All the repeats are contiguous and higher-order periodicities are superimposed on the octapeptide pattern throughout. Deletion analysis showed that most regions of the repeating structure are not essential for function. Up to 68 octapeptides could be deleted without abolishing ice nucleation, but all deletions showed reduced activity. This indicates that the repeated peptides contribute individually to the nucleation process, as expected if they act as individual units of a water-binding array.