<p><b>Motivation.</b> The detection of small molecules binding
sites in proteins is central to structure-based drug design and chemical
biology. Many tools were developed in the last 40 years, but few of them are still
available in 2020, open-source, and suitable for the analysis of large
databases or for the integration in automatic workflows. No software can
characterize subpockets solely with the information of the protein structure, a
pivotal concept in fragment-based drug design.</p>
<p><b>Results.</b> CAVIAR is a new open source tool for protein
<u>cav</u>ity <u>i</u>dentification <u>a</u>nd <u>r</u>ationalization,
supporting PDB and mmCIF files as well as DCD trajectories from molecular
dynamics simulations. The protein structure serves as input for automatic
cavity detection and computation of properties, including ligandability. A
subcavity segmentation algorithm decomposes binding sites into subpockets
without requiring the presence of a ligand. The defined subpockets mimick the
empirical definitions of subpockets in medicinal chemistry projects. A tool
like CAVIAR may be valuable to support chemical biology, medicinal chemistry
and ligand identification efforts. Our analysis of the PDB shows that liganded
cavities tend to be bigger, more hydrophobic and more complex than apo
cavities. Moreover, in line with the paradigm of fragment-based drug design,
the binding affinity scales relatively well with the number of subcavities
filled by the ligand. Compounds binding to more than three subcavities are
mostly in the nanomolar or better range of affinities to their target.</p>
<p><b>Availability and implementation. </b>Installation notes, user
manual and support for CAVIAR are available at <a href="https://jr-marchand.github.io/caviar/">https://jr-marchand.github.io/caviar/</a>.
The CAVIAR GUI and CAVIAR command line tool are available on GitHub at <a href="https://github.com/jr-marchand/caviar">https://github.com/jr-marchand/caviar</a>
and a conda package is hosted on Anaconda cloud at <a href="https://anaconda.org/jr-marchand/caviar">https://anaconda.org/jr-marchand/caviar</a>.
The software suite is free and all of the source code is available under a permissive
MIT license. The lists of PDB files used for validation, as well as the results
of subpocket decomposition with CAVIAR and DoGSite are hosted on GitHub at <a href="https://github.com/jr-marchand/caviar/tree/master/validation_sets">https://github.com/jr-marchand/caviar/tree/master/validation_sets</a>.</p>
<p><b>Contact: </b><a href="mailto:jean-remy.marchand@novartis.com">jean-remy.marchand@novartis.com</a>; <a href="mailto:finton.sirockin@novartis.com">finton.sirockin@novartis.com</a>
</p><br>