Part:BBa_K3790232

T7 gene product 5.7 driven by pBAD/araC

Introduction

In order to turn the host bacteria into ‘factories’ that concentrate on manufacturing parts of the virus, some phages have the ability to shut off the endogenous transcription of host bacteria. As for T7 phage, there’re three gene products collaboratively realizing the function, which are gp0.7, gp2 and gp5.7.

Gp0.7 and gp2 are early phage genes, which means they are transcribed by the hosts’ RNA polymerase at the very beginning of the infection process. Gp0.7 is a protein kinase without strong specificity. Some said that since it can phosphorylate RNAP of E.coli., it can somehow help inhibit the transcription, while others mentioned that there might be other mechanism. In general, the function of gp0.7 is complicated and not well studied yet. It can interfere with transcription somehow, but the effect is not notable enough.

Gp2 is a small protein that can bind to both the 1.1 domain of σ70 factor and the β’ subunit of the host’s RNAP, thus inhibiting the transcription initiated by σ70-RNAP complex very effectively.

However, in stressful conditions, such as platform stage, E.coli. will mainly use σS factors to initiate transcription, which makes gp2 less effective to shut off transcription. Therefore, gp5.7 is needed for phage to infect E.coli. in stationary phase of growth. Gp5.7 is coded by a mid-stage phage gene. It can bind to σS factors and RNAPs of E.coli. in order to inhibit the transcription initiated by σS-RNAP complex.

Part:BBa_K3790232

Introduction

Contents

Usage and Biology

Experimental Results

Reference