Heterogeneous diversity of spacers within CRISPR

TL;DR

This paper investigates the diversity of spacers in CRISPR systems, proposing a population dynamics model that explains the observed pattern of diversification and conservation along the CRISPR array, reflecting viral challenges.

Contribution

It introduces a new population dynamics model that accounts for the heterogeneity in spacer diversity within CRISPR arrays under viral pressure.

Findings

Leader-proximal end of CRISPR is more diversified.

Leader-distal end of CRISPR is more conserved.

Model aligns with recent experimental observations.

Abstract

Clustered regularly interspaced short palindromic repeats (CRISPR) in bacterial and archaeal DNA have recently been shown to be a new type of anti-viral immune system in these organisms. We here study the diversity of spacers in CRISPR under selective pressure. We propose a population dynamics model that explains the biological observation that the leader-proximal end of CRISPR is more diversified and the leader-distal end of CRISPR is more conserved. This result is shown to be in agreement with recent experiments. Our results show thatthe CRISPR spacer structure is influenced by and provides a record of the viral challenges that bacteria face.