Phylogeny of Cas1 proteins. Cas1 proteins encoded by casposons are represented in the framework of the Cas1 sequences representing the major types of CRISPR-Cas system. All clades including Cas1 from different CRISPR-Cas systems as well as Cas1-solo group 1 were collapsed for clarity (altogether, 52 non-casposon Cas1 sequences were analyzed, a representative subset of a larger collection of Cas1 sequences analyzed previously ; the Cas1 sequence alignment used to generate the tree is provided in Additional file 2, whereas the tree in which all branches are expanded is shown in Additional file 1: Figure S5). Numbers at the branch points represent RELL (resampling of estimated log-likelihoods)-like local support values calculated by FastTree.
Krupovic et al. BMC Biology 2014 12:36 doi:10.1186/1741-7007-12-36