View source for 1mjo

[[Image:1mjo.gif|left|200px]]<br /><applet load="1mjo" size="450" color="white" frame="true" align="right" spinBox="true" 
caption="1mjo, resolution 2.10&Aring;" />
'''METHIONINE HOLOREPRESSOR MUTANT (Q44K) PLUS COREPRESSOR (S-ADENOSYL METHIONINE) COMPLEXED TO THE MINIMAL MET CONSENSUS OPERATOR WITH THE CENTRAL TA STEP MUTATED TO AT'''<br />

==Overview==
BACKGROUND: The methionine repressor, MetJ, represses the transcription of, genes involved in methionine biosynthesis by binding to arrays of two to, five adjacent copies of an eight base-pair 'metbox' sequence. Naturally, occurring operators differ from the consensus sequence to a greater extent, as the number of metboxes increases. MetJ, while accommodating this, sequence variation in natural operators, is very sensitive to particular, base changes, even where bases are not directly contacted in the crystal, structure of a complex formed between the repressor and consensus, operator. RESULTS: Here we report the high-resolution structure of a MetJ, mutant, Q44K, bound to the consensus operator sequence (Q44Kwt19) and two, related sequences containing mutations at sites believed to be important, for indirect readout at non-contacted bases. The overall structure of the, Q44Kwt19 complex is very similar to the wild-type complex, but there are, small variations in sugar-phosphate backbone conformation and direct, contacts to the DNA bases. The mutant complexes show a mixture of direct, and indirect readout of sequence variations, with differences in direct, contacts and DNA conformation. CONCLUSIONS: Comparison of the wild-type, and mutant repressor-operator complexes shows that the repressor makes, sufficiently strong interactions with the sugar-phosphate backbone to, accommodate some variation in operator sequence with minor changes in, direct bases contacts. The reduction in repressor affinity for the two, mutant repressor complexes can be partially attributed to a loss in direct, contacts to the DNA. In one case, however, the replacement of a flexible, TA base-step leads to an unfavourable DNA conformation that reduces the, stability of the repressor-operator complex.

==About this Structure==
1MJO is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] with CA and SAM as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1MJO OCA]. 

==Reference==
Direct and indirect readout in mutant Met repressor-operator complexes., Garvie CW, Phillips SE, Structure. 2000 Sep 15;8(9):905-14. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=10986458 10986458]
[[Category: Escherichia coli]]
[[Category: Single protein]]
[[Category: Garvie, C.W.]]
[[Category: Phillips, S.E.V.]]
[[Category: CA]]
[[Category: SAM]]
[[Category: complex (transcription regulation/dna)]]
[[Category: dna]]
[[Category: methionine repressor]]
[[Category: metj]]
[[Category: s-adenosyl methionine]]
[[Category: sheet-helix-helix]]
[[Category: transcription regulation]]

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