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Investigating the Antimicrobial Activity of Two Mycobacteriophage-encoded Lysterases

Barbeau, Dominique (2017) Investigating the Antimicrobial Activity of Two Mycobacteriophage-encoded Lysterases. Master's Thesis, University of Pittsburgh. (Unpublished)

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All double-stranded DNA bacteriophages encode a specialized set of proteins that allow progeny phages to escape the current host cell at the end of the lytic cycle. At a minimum, this lytic cassette consists of a holin and an endolysin to destabilize the host’s plasma membrane and peptidoglycan layer, respectively. This two-enzyme system is sufficient to break open most Gram-positive hosts, but the phages of bacteria with more complex cell walls often encode additional lysis proteins. For example, the mycobacteria have thick, waxy, mycolic acid-rich cell walls that aid in their antibiotic resistance. Therefore, their phages—the mycobacteriophages—also encode a lysterase (LysB), in order to efficiently overcome this barrier. In vitro, these serine esterase proteins have been shown to hydrolyze mycolic acids from whole mycobacterial cells and purified cell wall components. Our data also show that exogenous addition of purified lysterases has antimicrobial activity against several species within the Order Actinomycetales, including bacteria associated with disease and—surprisingly—bacteria that do not contain mycolic acids, such as Cutibacterium acnes. C. acnes is the implicated causative bacteria in the skin disease acne vulgaris and is an opportunistic pathogen in eye, blood, and medical device infections. While the identity of the LysB target on C. acnes is still unknown, we have tested LysB activity against multiple clinically relevant strains of C. acnes and have shown that LysB treatment releases an unidentified lipid from whole C. acnes cells.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Barbeau, Dominiquedjb117@pitt.edudjb117
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairHatfull, Grahamgfh@pitt.edugfh
Committee MemberLawrence, Jeffreyjlawrenc@pitt.edujlawrenc
Committee MemberHendrix, Rogerrhx@pitt.edurhx
Committee MemberPeebles, Craigcpeebles@pitt.educpeebles
Date: 29 September 2017
Date Type: Publication
Defense Date: 27 July 2017
Approval Date: 29 September 2017
Submission Date: 8 August 2017
Access Restriction: 1 year -- Restrict access to University of Pittsburgh for a period of 1 year.
Number of Pages: 61
Institution: University of Pittsburgh
Schools and Programs: Dietrich School of Arts and Sciences > Biological Sciences
Degree: MS - Master of Science
Thesis Type: Master's Thesis
Refereed: Yes
Uncontrolled Keywords: mycobacteria, mycobacteriophage, lysis, acne, lysterase, lysin B
Date Deposited: 29 Sep 2017 19:37
Last Modified: 29 Sep 2018 05:15


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