Identifying protein construct variants with increased crystallization propensity--a case study.
This study describes an efficient multiparallel automated workflow of cloning, expression, purification, and crystallization of a large set of construct variants for isolated protein domains aimed at structure determination by X-ray crystallography. This methodology is applied to MAPKAP kinase 2, a key enzyme in the inflammation pathway and thus an attractive drug target. The study reveals a distinct subset of truncation variants with improved crystallization properties. These constructs distinguish themselves by increased solubility and stability during a parallel automated multistep purification process including removal of the recombinant tag. High-throughput protein melting point analysis characterizes this subset of constructs as particularly thermostable. Both parallel purification screening and melting point determination clearly identify residue 364 as the optimal C terminus for the kinase domain. Moreover, all three constructs that ultimately crystallized feature this C terminus. At the N terminus, only three amino acids differentiate a noncrystallizing from a crystallizing construct. This study addresses the very common issues associated with difficult to crystallize proteins, those of solubility and stability, and the crucial importance of particular residues in the formation of crystal contacts. A methodology is suggested that includes biophysical measurements to efficiently identify and produce construct variants of isolated protein domains which exhibit higher crystallization propensity.
Malawski
Guido A
GA
Schering AG, Research Center Europe, 13342 Berlin, Germany.
Hillig
Roman C
RC
Monteclaro
Felipe
F
Eberspaecher
Uwe
U
Schmitz
Arndt A P
AA
Crusius
Kerstin
K
Huber
Martina
M
Egner
Ursula
U
Donner
Peter
P
Müller-Tiemann
Beate
B
D003001:Cloning, Molecular; D003460:Crystallization / Q000379:methods*; D004795:Enzyme Stability; D014644:Genetic Variation / Q000502:physiology*; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008958:Models, Molecular; D050505:Mutant Proteins / Q000737:chemistry; D011487:Protein Conformation; D011489:Protein Denaturation; D011494:Protein Kinases / Q000737:chemistry* / Q000235:genetics*; D017346:Protein Serine-Threonine Kinases; D011994:Recombinant Proteins / Q000737:chemistry; D013696:Temperature; D000099190:MAP-Kinase-Activated Kinase 2
D047908:Intracellular Signaling Peptides and Proteins; D050505:Mutant Proteins; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases; D011994:Recombinant Proteins; D000099190:MAP-Kinase-Activated Kinase 2