ATPase: Difference between revisions
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'''Structural and functional insights into a dodecameric molecular machine – The RuvBL1/RuvBL2 complex (ATPase)<ref >PMID: 21933716</ref>'''<br /> | '''Structural and functional insights into a dodecameric molecular machine – The RuvBL1/RuvBL2 complex (ATPase)<ref >PMID: 21933716</ref>'''<br /> | ||
<scene name='Journal:JSB:1/Al/1'>RuvBL1</scene> (RuvB-like 1; [[2c9o]] <ref>PMID: 17060327</ref>; <font color='magenta'><b>colored magenta</b></font>) and its homolog RuvBL2 are evolutionarily highly conserved AAA+ '''ATPases''' essential for many cellular activities. They play an important role in chromatin remodeling, transcriptional regulation and DNA damage repair. RuvBL1 and RuvBL2 are overexpressed in different types of cancer and interact with major oncogenic factors, such as β-catenin and c-myc regulating their function. Since the full-length complex did not crystallize, <scene name='Journal:JSB:1/Al/6'>mutants of RuvBL1 and RuvBL2 with a two-thirds truncation of the flexible domain II</scene> were generated: <scene name='Journal:JSB:1/Al/3'>RuvBL1deltaDII</scene> <font color='darkmagenta'><b>(R1∆DII)</b></font> and <scene name='Journal:JSB:1/Al/5'>RuvBL2deltaDII</scene> < | <scene name='Journal:JSB:1/Al/1'>RuvBL1</scene> (RuvB-like 1; [[2c9o]] <ref>PMID: 17060327</ref>; <font color='magenta'><b>colored magenta</b></font>) and its homolog RuvBL2 are evolutionarily highly conserved AAA+ '''ATPases''' essential for many cellular activities. They play an important role in chromatin remodeling, transcriptional regulation and DNA damage repair. RuvBL1 and RuvBL2 are overexpressed in different types of cancer and interact with major oncogenic factors, such as β-catenin and c-myc regulating their function. Since the full-length complex did not crystallize, <scene name='Journal:JSB:1/Al/6'>mutants of RuvBL1 and RuvBL2 with a two-thirds truncation of the flexible domain II</scene> were generated: <scene name='Journal:JSB:1/Al/3'>RuvBL1deltaDII</scene> <font color='darkmagenta'><b>(R1∆DII)</b></font> and <scene name='Journal:JSB:1/Al/5'>RuvBL2deltaDII</scene> <span style="color:cyan;background-color:black;font-weight:bold;">(R2∆DII)</span>. Crystals of the selenomethionine derivative of the R1∆DII/R2∆DII complex diffracted to 3 Å resolution and led to the determination of the three-dimensional structure of the complex. The structure reveals a <scene name='Journal:JSB:1/Cv/2'>dodecamer consisting of two heterohexameric rings with alternating RuvBL1 and RuvBL2 monomers</scene> (the <font color='darkmagenta'><b>RuvBL1</b></font> and the <span style="color:cyan;background-color:black;font-weight:bold;">RuvBL2</span> <scene name='Journal:JSB:1/Cv/3'>monomers in the dodecamer</scene> are colored <font color='darkmagenta'><b>darkmagenta</b></font> and <span style="color:cyan;background-color:black;font-weight:bold;">cyan</span>, respectively) bound to ADP/ATP (click on <scene name='Journal:JSB:1/Cv/5'>RuvBL1 </scene> or, alternatively on <scene name='Journal:JSB:1/Cv/6'>RuvBL2</scene> to see protein/nucleotide interactions). The two heterohexamers interact with each other via the retained part of domain II, which is however poorly visible in the electron density maps, probably because the complex was not crystallized in a single conformational state. This is also hinted by evidence that in the RuvBL1 monomers, ATP was partly hydrolyzed to ADP. The dodecameric quaternary structure of the R1ΔDII/R2ΔDII complex observed in the crystal structure was confirmed by small-angle X-ray scattering analysis. RuvBL1 and RuvBL2 share <scene name='Journal:JSB:1/Al/7'>43 % sequence identity and 65 % sequence similarity and therefore the 3D structures of R1deltaDII and R2deltaDII are very similar</scene>. Due to the low data resolution, and even though the crystal structure could be solved by molecular replacement using a truncated RuvBL1 model, the use of a selenomethionine derivative was essential to elucidate the complex composition, since only one methionine residue is conserved out of 11 in R1ΔDII and 12 in R2ΔDII. | ||
Interestingly, truncation of domain II led to a substantial increase in ATP consumption of RuvBL1, RuvBL2 and their complex. In addition, we present evidence that DNA unwinding of the human RuvBL proteins can be auto-inhibited by domain II, which is not present in the homologous bacterial helicase RuvB. The alternation of charges in the central channel of the dodecamer shown below, combined with the diameter of the channel (ranging between 17 and 21 Å) suggests interactions with single-stranded nucleic acids. | Interestingly, truncation of domain II led to a substantial increase in ATP consumption of RuvBL1, RuvBL2 and their complex. In addition, we present evidence that DNA unwinding of the human RuvBL proteins can be auto-inhibited by domain II, which is not present in the homologous bacterial helicase RuvB. The alternation of charges in the central channel of the dodecamer shown below, combined with the diameter of the channel (ranging between 17 and 21 Å) suggests interactions with single-stranded nucleic acids. | ||
[[Image:Figure_S6.png|left|500px|thumb|Electrostatic potential mapped at the molecular surface for the R1deltaDII/R2deltaDII dodecamer. (a) top view and (b) cross-section view showing the central channel. (c) cross-section view of the SV40 Ltag | [[Image:Figure_S6.png|left|500px|thumb|Electrostatic potential mapped at the molecular surface for the R1deltaDII/R2deltaDII dodecamer. (a) top view and (b) cross-section view showing the central channel. (c) cross-section view of the SV40 Ltag | ||