Determining nucleotide analog specificity for SAMHD1. Joseph A. Hollenbaugh Jadd Shelton Sijia Tao Sheida Amiralaei Peng Liu Xiao Lu Russell W. Goetze Longhu Zhou James H. Nettles Raymond F. Schinazi Baek Kim 10.1371/journal.pone.0169052.g008 https://plos.figshare.com/articles/figure/Determining_nucleotide_analog_specificity_for_SAMHD1_/4512425 <p>A) Modification of the 2' sugar position of a nucleotide can lead to several different outcomes. First, (2'<i>R</i>)-2'-F and (2'<i>R</i>)-2'-OH sugar moieties have been shown not to be substrates for SAMHD1. Additional analogs with (2'<i>R</i>)-2'-F and (2'<i>R</i>)-2'-OH sugar moieties would be predicted not to be substrates for SAMHD1. Second, canonical dNTPs and the non-canonical dUTP are substrates for SAMHD1. Our data shows that ((2'<i>S</i>)-2'-OH) arabinose nucleoside-5'-triphosphates are also substrates for SAMHD1. Therefore, we also predict several other arabinose nucleoside analogs would be substrates for SAMHD1. Moreover, clofarabine-TP ((2'<i>S</i>)-2'-F) was reported hydrolyzed by SAMHD1 [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0169052#pone.0169052.ref043" target="_blank">43</a>]. Finally, we found the SMDU-TP, (2'<i>R</i>)-2'-methyl sugar moiety, inhibited the triphosphohydrolase activity of SAMHD1. We postulate that the (2'<i>R</i>)-2'-methyl moiety may prevent the conformational change in the catalytic site of SAMHD1 due to the size of the methyl group clashing with Y374. Therefore, we predicted that nucleotides with a (2'<i>S</i>)-2'-cyano moiety may also inhibit dNTPase activity of SAMHD1. B) A SAMHD1 inhibitor has been reported [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0169052#pone.0169052.ref034" target="_blank">34</a>]. The pppCH<sub>2</sub>-dU analog has a 5'-methylene modification, making the analog non-hydrolysable in the catalytic site, but also was shown to block homotetramerization when present in the A2 site [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0169052#pone.0169052.ref034" target="_blank">34</a>]. C) Modification of the 3'-OH sugar moiety is not permissive. NRTIs and ddNTPs lack a 3'-OH moiety, making them chain terminators for DNA polymerases, are not substrates for SAMHD1. D) Base modifications for different nucleoside analogs are permissive substrates for SAMHD1.</p> 2017-01-03 19:16:21 L 150 exclusion 351-V OH SAMHD 1. Importantly SAMHD 1 nucleotide substrate specificity SMDU-TP SAMHD 1.