Tilly K, Elias A F, Errett J, Fischer E, Iyer R, Schwartz I, Bono J L, Rosa P
Laboratory of Human Bacterial Pathogenesis, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rocky Mountain Laboratories, Hamilton, Montana 59840, USA.
J Bacteriol. 2001 Oct;183(19):5544-53. doi: 10.1128/JB.183.19.5544-5553.2001.
Borrelia burgdorferi spends a significant proportion of its life cycle within an ixodid tick, which has a cuticle containing chitin, a polymer of N-acetylglucosamine (GlcNAc). The B. burgdorferi celA, celB, and celC genes encode products homologous to transporters for cellobiose and chitobiose (the dimer subunit of chitin) in other bacteria, which could be useful for bacterial nutrient acquisition during growth within ticks. We found that chitobiose efficiently substituted for GlcNAc during bacterial growth in culture medium. We inactivated the celB gene, which encodes the putative membrane-spanning component of the transporter, and compared growth of the mutant in various media to that of its isogenic parent. The mutant was no longer able to utilize chitobiose, while neither the mutant nor the wild type can utilize cellobiose. We propose renaming the three genes chbA, chbB, and chbC, since they probably encode a chitobiose transporter. We also found that the chbC gene was regulated in response to growth temperature and during growth in medium lacking GlcNAc.
伯氏疏螺旋体在其生命周期的很大一部分时间内存在于硬蜱体内，硬蜱的角质层含有几丁质，它是N - 乙酰葡糖胺（GlcNAc）的聚合物。伯氏疏螺旋体的celA、celB和celC基因编码的产物与其他细菌中纤维二糖和壳二糖（几丁质的二聚体亚基）的转运蛋白同源，这可能有助于细菌在蜱体内生长期间获取营养。我们发现壳二糖在细菌在培养基中生长期间能有效地替代GlcNAc。我们使编码假定转运蛋白跨膜成分的celB基因失活，并将突变体在各种培养基中的生长与其同基因亲本的生长进行比较。突变体不再能够利用壳二糖，而突变体和野生型均不能利用纤维二糖。我们建议将这三个基因重新命名为chbA、chbB和chbC，因为它们可能编码一种壳二糖转运蛋白。我们还发现chbC基因受生长温度以及在缺乏GlcNAc的培养基中生长的影响而受到调控。
