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This Week in Science: Jul 21, 2017

In Science this week, the University of California, Berkeley's Jennifer Douda and colleagues report the crystal structures of two Cas enzymes involved in CRISPR genome editing, as well as cryo-electron microscopy structure of the full CRISPR locus integration complex, providing new insights into how components of the system interact with one another as a viral defense mechanism for bacteria. Their findings suggest that CRISPR-Cas1-Cas2 interacts with DNA based on its structural features, rather than the direct recognition of its sequence as previously thought. Additionally, the work indicates that CRISPR systems appear to have take advantage of the requirement for DNA bending to provide sequence specificity — something that could be used by scientists for genome tagging applications. Overall, the study explains "how the Cas1-Cas2 CRISPR integrase recognizes a sequence-dependent DNA structure to ensure site-selective CRISPR array expansion during the initial step of bacterial adaptive immunity," the authors write.

And in an editorial in Science, researchers from the University of Washington and Stanford University discuss the need for greater transparency, consistency, and completeness from scientific journals with respect to their review standards. Although peer-reviewed publications are promoting policies for transparency and openness, the authors argue that little is being done to test whether policies actually work. Among other things, they call for publishers to take an active role by providing resources to journal editors to evaluate peer-review processes, as well as for a guideline structure that allows a journal to choose different degrees of transparency in order to allow it to signal its commitment to self-assessment and improvement. "As pressures on journals, publishers, and authors continue to shift, it may be time to apply the 'trust, but verify' model to journal peer review," the authors state. "Doing so is essential for closing the gap between guidance recommendations and observed reporting behavior."