Slocum M K, Parkinson J S
J Bacteriol. 1985 Aug;163(2):586-94. doi: 10.1128/jb.163.2.586-594.1985.
The tar and tap genes are located adjacent to one another in an operon of chemotaxis-related functions. They encode methyl-accepting chemotaxis proteins implicated in tactic responses to aspartate and maltose stimuli. The functional roles of these two gene products were investigated by isolating and characterizing nonpolar, single-gene deletion mutants at each locus. Deletions were obtained by selecting for loss or a defective Mu d1 prophage inserted in either the tar or tap gene. The extent of the tar deletions was determined by genetic mapping with Southern hybridization. Representative deletion mutants were surveyed for chemotactic responses on semisolid agar and by temporal stimulation in a tethered cell assay to assess flagellar rotational responses to chemoeffector compounds. The tar deletion strains exhibited complete loss of aspartate and maltose responses, whereas the tap deletion strains displayed a wild-type phenotype under all conditions tested. These findings indicate that the tap function is unable to promote chemotactic responses to aspartate and maltose, and its role in chemotaxis remains unclear.
tar基因和tap基因在一个与趋化功能相关的操纵子中彼此相邻。它们编码甲基接受趋化蛋白，这些蛋白与对天冬氨酸和麦芽糖刺激的趋化反应有关。通过分离和鉴定每个位点的非极性单基因缺失突变体，研究了这两种基因产物的功能作用。通过选择插入tar或tap基因中的Mu d1原噬菌体的缺失或缺陷来获得缺失。通过Southern杂交进行遗传图谱分析来确定tar缺失的程度。对代表性的缺失突变体进行半固体琼脂上的趋化反应调查，并在拴系细胞试验中进行时间刺激，以评估鞭毛对化学效应化合物的旋转反应。tar缺失菌株表现出对天冬氨酸和麦芽糖反应的完全丧失，而tap缺失菌株在所有测试条件下均表现出野生型表型。这些发现表明，tap功能无法促进对天冬氨酸和麦芽糖的趋化反应，其在趋化作用中的作用仍不清楚。
