Homing Endonuclease I-TevI: An Atypical Zinc Finger with a Novel Function

Roey, P. Van; Belfort, Marlene; Derbyshire, Victoria

doi:10.1007/0-387-27421-9_7

Cited by 1 publication

(1 citation statement)

References 12 publications

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“…This arrangement is reminiscent of a zinc finger in the DNA binding domain of the homing endonuclease iTev-I (a distant relation, but the most well-characterized protein somewhat similar to ICP1 putative HEGs), which contains a small degenerate treble-clef fold with four similarly-arranged cysteines coordinating a zinc ion. The zinc finger subdomain makes two direct hydrogen bond contacts with DNA, suggesting that the subdomain may be capable of independent DNA binding and that zinc coordination by the four cysteine residues is likely critical to that activity ( 32 ).…”

Section: Resultsmentioning

confidence: 99%

A phage satellite tunes inducing phage gene expression using a domesticated endonuclease to balance inhibition and virion hijacking

Netter

Boyd

Silvas

et al. 2021

Nucleic Acids Research

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Bacteria persist under constant threat of predation by bacterial viruses (phages). Bacteria-phage conflicts result in evolutionary arms races often driven by mobile genetic elements (MGEs). One such MGE, a phage satellite in Vibrio cholerae called PLE, provides specific and robust defense against a pervasive lytic phage, ICP1. The interplay between PLE and ICP1 has revealed strategies for molecular parasitism allowing PLE to hijack ICP1 processes in order to mobilize. Here, we describe the mechanism of PLE-mediated transcriptional manipulation of ICP1 structural gene transcription. PLE encodes a novel DNA binding protein, CapR, that represses ICP1’s capsid morphogenesis operon. Although CapR is sufficient for the degree of capsid repression achieved by PLE, its activity does not hinder the ICP1 lifecycle. We explore the consequences of repression of this operon, demonstrating that more stringent repression achieved through CRISPRi restricts both ICP1 and PLE. We also discover that PLE transduces in modified ICP1-like particles. Examination of CapR homologs led to the identification of a suite of ICP1-encoded homing endonucleases, providing a putative origin for the satellite-encoded repressor. This work unveils a facet of the delicate balance of satellite-mediated inhibition aimed at blocking phage production while successfully mobilizing in a phage-derived particle.

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Section: Resultsmentioning

confidence: 99%