Chandry P S, Davidson B E, Hillier A J
Commonwealth Scientific and Industrial Research Organization, Division of Food Science and Technology, Highett, Victoria, Australia.
Microbiology (Reading). 1994 Sep;140 ( Pt 9):2251-61. doi: 10.1099/13500872-140-9-2251.
Bacteriophage sk1 is a small isometric-headed lytic phage that infects Lactococcus lactis. The phage has a linear double-stranded DNA genome of 28 kbp, with cohesive ends. RNA was prepared from phage-infected L. lactis cells harvested at various intervals after infection, and the RNA molecules were resolved by electrophoresis. Northern blots of these gels were hybridized with sk1 DNA probes and the results obtained from these experiments, together with the results of primer extension analyses, enabled a transcription map of the phage genome to be prepared. Three classes of phage transcripts, designated as early, middle or late based on their time of appearance, were detected. Seven partially overlapping early transcripts were detected; these were transcribed from a 10 kbp region of the phage. The nine middle transcripts were derived from a 2 kbp region, limited by cos at one end and the start of the early transcripts at the other. The early and middle transcripts were transcribed divergently from a region mapping at 26 kbp on the sk1 physical map. The four late transcripts were derived from a 16 kbp region of the phage limited at one end by cos. The late transcripts were transcribed in the opposite direction to the early transcripts and three of the late transcripts terminated in the same region of the phage genome as three of the early transcripts.
噬菌体sk1是一种小型等轴头裂解性噬菌体，可感染乳酸乳球菌。该噬菌体具有一个28 kbp的线性双链DNA基因组，两端为粘性末端。从感染后不同时间收获的噬菌体感染的乳酸乳球菌细胞中制备RNA，并通过电泳分离RNA分子。用sk1 DNA探针与这些凝胶的Northern印迹杂交，这些实验获得的结果以及引物延伸分析的结果，使得能够制备噬菌体基因组的转录图谱。检测到三类噬菌体转录本，根据其出现时间分为早期、中期或晚期。检测到七个部分重叠的早期转录本；它们是从噬菌体的一个10 kbp区域转录而来的。九个中期转录本来自一个2 kbp区域，一端受粘性末端限制，另一端受早期转录本起始位点限制。早期和中期转录本从sk1物理图谱上位于26 kbp的一个区域向不同方向转录。四个晚期转录本来自噬菌体的一个16 kbp区域，一端受粘性末端限制。晚期转录本的转录方向与早期转录本相反，并且三个晚期转录本在噬菌体基因组的同一区域终止，与三个早期转录本相同。
