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You searched for subject:(Phage T4 Portal). One record found.

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1. Tang, WeiChun. Functional Roles of Bacteriophage T4 Portal Protein in Genome Packaging.

Degree: 2019, The Catholic University of America

As one of the most abundant life forms in the biosphere, tailed bacteriophages (phages) such as phage T4 multiply in a bacterial host and release ~200 progeny phages per bacterial cell in ~30 minutes. Phage T4 infects the Escherichia coli bacterium and encapsidates ~58 μm long, 170-kbp double stranded DNA genome in a 120 x 86 nm capsid using a powerful molecular motor. It is estimated that about 100,000 ATP fuel molecules are consumed to package one phage T4 genome. With packaging rates up to ~2,000 bp/sec and power density of ~5000 kW/m3, the T4 packaging motor is the fastest and most powerful molecular motor reported to date. Five molecules of the motor protein (gp17) dock on a dodecameric portal (gp20) present at the unique vertex of the capsid to initiate DNA packaging. Together, the motor and the portal form the phage DNA packaging machine.The main goal of the present thesis is to elucidate the functional roles of phage T4 portal vertex using a combination of genetic, biochemical, and structural approaches. Structural analyses revealed that the subunits of dodecameric portal are held together by a series of salt bridges, a feature conserved in all portal structures. Molecular genetic experiments demonstrated that the intersubunit salt bridges in “clip” portal domain, the domain that interacts with motor, are critical for portal function. Biochemical assays suggested that these salt bridge mutants are defective in head assembly and DNA packaging. Single molecule studies indicated that the mutants are defective in initiating DNA packaging. A series of second site suppressors isolated starting with a key defective salt bridge between Asp361 of one subunit and Arg275 of the adjacent subunit showed temperature sensitive phenotypes. DNA sequencing of suppressor mutants identified amino acid substitutions in several other portal domains as well as in the packaging motor. These results implicate long-distance effects between various portal domains, and between the portal and the motor, which regulate the DNA packaging mechanism. A minimal two-state model is proposed in which the portal vertex alternates between two conformations through re-modeling of the salt bridges, in coordination with the DNA grip and release functions of the packaging motor.

Molecular biology

Virology

DNA Packaging, Phage T4 Portal

Biology

Degree Awarded: Ph.D. Biology. The Catholic University of America

Advisors/Committee Members: The Catholic University of America (Degree granting institution), Rao, Venigalla (Thesis advisor), Nestorovich, Ekaterina (Committee member), Chung, Byung Min (Justin) (Committee member).

Subjects/Keywords: DNA Packaging; Phage T4 Portal

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Tang, W. (2019). Functional Roles of Bacteriophage T4 Portal Protein in Genome Packaging. (Thesis). The Catholic University of America. Retrieved from http://hdl.handle.net/1961/cuislandora:213706

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Tang, WeiChun. “Functional Roles of Bacteriophage T4 Portal Protein in Genome Packaging.” 2019. Thesis, The Catholic University of America. Accessed May 09, 2021. http://hdl.handle.net/1961/cuislandora:213706.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Tang, WeiChun. “Functional Roles of Bacteriophage T4 Portal Protein in Genome Packaging.” 2019. Web. 09 May 2021.

Vancouver:

Tang W. Functional Roles of Bacteriophage T4 Portal Protein in Genome Packaging. [Internet] [Thesis]. The Catholic University of America; 2019. [cited 2021 May 09]. Available from: http://hdl.handle.net/1961/cuislandora:213706.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Tang W. Functional Roles of Bacteriophage T4 Portal Protein in Genome Packaging. [Thesis]. The Catholic University of America; 2019. Available from: http://hdl.handle.net/1961/cuislandora:213706

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

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