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Abstract：
Mycobacteriophages are viruses that specifically infect bacterial species within the genera Mycobacterium and Mycolicibacterium. Over 2400 mycobacteriophages have been isolated on the host Mycolicibacterium smegmatis and sequenced. This wealth of genomic data indicates that mycobacteriophage genomes are diverse, mosaic, and contain numerous (35-60%) genes for which there is no predicted function based on sequence similarity to characterized orthologs, many of which are essential to lytic growth. To fully understand the molecular aspects of mycobacteriophage-host interactions, it is paramount to investigate the function of these genes and gene products. Here we show that the temperate mycobacteriophage, Alexphander, makes stable lysogens with a frequency of 2.8%. Alexphander gene 94 is essential for lytic infection and encodes a protein predicted to contain a C-terminal MerR family helix-turn-helix DNA-binding motif (HTH) and an N-terminal DinB/YfiT motif, a putative metal-binding motif found in stress-inducible gene products. Full-length and C-terminal gp94 constructs form high-order nucleoprotein complexes on 100-500 base pair double-stranded DNA fragments and full-length phage genomic DNA with little sequence discrimination for the DNA fragments tested. Maximum gene 94 mRNA levels are observed late in the lytic growth cycle, and gene 94 is transcribed in a message with neighboring genes 92 through 96. We hypothesize that gp94 is an essential DNA-binding protein for Alexphander during lytic growth. We proposed that gp94 forms multiprotein complexes on DNA through cooperative interactions involving its HTH DNA-binding motif at sites throughout the phage chromosome, facilitating essential DNA transactions required for lytic propagation.
摘要：
分枝杆菌噬菌体是特异性感染分枝杆菌属和分枝杆菌属内的细菌物种的病毒。已在宿主耻垢分枝杆菌上分离出超过2400个分枝杆菌噬菌体并进行了测序。这些丰富的基因组数据表明分枝杆菌噬菌体基因组是多样化的，马赛克,并且包含许多（35-60％）基因，这些基因没有基于与表征的直系同源物的序列相似性的预测功能，其中许多对裂解生长至关重要。为了充分了解分枝杆菌噬菌体-宿主相互作用的分子方面，研究这些基因和基因产物的功能是至关重要的。这里我们展示了温带分枝杆菌噬菌体，Alexphander,产生频率为2.8%的稳定溶原。Alexphander基因94对于溶解性感染至关重要，并且编码一种蛋白质，该蛋白质被预测包含C端MerR家族螺旋-转角-螺旋DNA结合基序（HTH）和N端DinB/YfiT基序，在应激诱导基因产物中发现的推定的金属结合基序。全长和C端gp94构建体在100-500个碱基对的双链DNA片段和全长噬菌体基因组DNA上形成高阶核蛋白复合物，对所测试的DNA片段几乎没有序列区分。在裂解生长周期的后期观察到最高基因94mRNA水平，基因94与邻近基因92到96转录成一条信息。我们假设gp94是Alexphander在裂解生长过程中必需的DNA结合蛋白。我们提出gp94通过涉及其HTHDNA结合基序在整个噬菌体染色体位点的协同相互作用在DNA上形成多蛋白复合物，促进裂解繁殖所需的基本DNA交易。
