Gurian-Sherman D, Lindow S E
Department of Plant Pathology, University of California, Berkeley 94720.
FASEB J. 1993 Nov;7(14):1338-43. doi: 10.1096/fasebj.7.14.8224607.
Several bacterial species are able to catalyze ice formation at temperatures as warm as -2 degrees C. These microorganisms efficiently catalyze ice formation at temperatures much higher than most organic or inorganic substances. Because of their ubiquity on the surfaces of frost-sensitive plants, they are responsible for initiating ice formation, which results in frost injury. The high temperature of ice catalysis conferred by bacterial ice nuclei makes them useful in ice nucleation-limited processes such as artificial snow production, the freezing of some food products, and possibly in future whether modification schemes. The rarity of other ice nuclei active at high subfreezing temperature, and the ease and sensitivity with which ice nuclei can be quantified, have made the use of a promoterless bacterial ice nucleation gene valuable as a reporter of transcription. Target genes to which this promoter is fused can be used in cells in natural habitats. Warm-temperature ice nucleation sites have also been extensively studied at a molecular level. Nucleation sites active at high temperatures (above -5 degrees C) are probably composed of bacterial ice nucleation protein molecules that form functionally aligned aggregates. Models of ice nucleation proteins predict that they form a planar array of hydrogen binding groups that closely complement that of an ice crystal face. Moreover, interdigitation of these molecules may produce a large contiguous template for ice formation.
有几种细菌能够在低至 -2摄氏度的温度下催化冰的形成。这些微生物能够在比大多数有机或无机物质高得多的温度下有效地催化冰的形成。由于它们在对霜冻敏感的植物表面普遍存在，它们会引发冰的形成，从而导致霜冻伤害。细菌冰核赋予的冰催化高温特性使其在诸如人工造雪、某些食品冷冻以及未来可能的气候改造方案等冰核限制过程中具有应用价值。在亚冰点高温下具有活性的其他冰核很少见，而且冰核的量化简便且灵敏，这使得无启动子的细菌冰核基因作为转录报告基因很有价值。与该启动子融合的靶基因可用于自然栖息地的细胞中。高温冰核位点也已在分子水平上得到广泛研究。在高温（高于 -5摄氏度）下具有活性的冰核位点可能由形成功能排列聚集体的细菌冰核蛋白分子组成。冰核蛋白模型预测，它们形成了与冰晶面紧密互补的氢键结合基团平面阵列。此外，这些分子的交叉排列可能会产生一个用于冰形成的大的连续模板。
