Date of Award

2021-12-01

Degree Name

Doctor of Philosophy

Department

Chemistry

Advisor(s)

Chu-Young Kim

Abstract

Class II UvrA is an ATP-binding cassette protein and a homolog of class I UvrA, the DNA lesion detection component of the universal prokaryotic nucleotide excision repair system. We show that Ecm16, a class II UvrA protein from Streptomyces lasalocidi, specifically recognizes DNA duplex that contains the DNA bisintercalator antibiotic echinomycin. Heterologous expression of Ecm16 in Escherichia coli renders host cells resistant to echinomycin. Interestingly, Ecm16’s antibiotic resistance activity does not require the DNA repair proteins UvrA/B/C/D, indicating that it operates independently of the cell’s nucleotide excision repair pathway. Unlike UvrA, Ecm16 uses the insertion domain to regulate its ATPase activity dependent on the type of substrate (damaged vs. undamaged DNA). We have determined the crystal structure of Ecm16 at 2.0 Å resolution. Although Ecm16’s structure is highly similar to that of UvrA, Ecm16 lacks the UvrB-binding domain and its associated Zinc-binding module found in all UvrA proteins, and its insertion domain appears to be mobile. We showed that Ecm16 can bind echinomycin independent of DNA. Ecm16, when expressed in Brevibacillus system provides partial resistance against other DNA bisintercalators like quinaldopeptin, thiocoraline and sandramycin. Our work has revealed that Streptomyces lasalocidi has evolved a unique pathway to counter the assault of the DNA bisintercalator antibiotic.

Language

en

Provenance

Recieved from ProQuest

File Size

111 p.

File Format

application/pdf

Rights Holder

priyanka Rajendra gade

Included in

Biochemistry Commons

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