scholarly journals Mutational analysis of the DNA binding domain A of chromosomal protein HMG1

1994 ◽  
Vol 22 (3) ◽  
pp. 285-292 ◽  
Author(s):  
Luca Falciola ◽  
Alastair I.H. Murchie ◽  
David M.J. Lilley ◽  
Marco E. Bianchi
2000 ◽  
Vol 182 (24) ◽  
pp. 6975-6982 ◽  
Author(s):  
Janet K. Hatt ◽  
Philip Youngman

ABSTRACT The Spo0A protein of Bacillus subtilis is a DNA-binding protein that is required for the expression of genes involved in the initiation of sporulation. Spo0A binds directly to and both activates and represses transcription from the promoters of several genes required during the onset of endospore formation. The C-terminal 113 residues are known to contain the DNA-binding activity of Spo0A. Previous studies identified a region of the C-terminal half of Spo0A that is highly conserved among species of endospore-formingBacillus and Clostridium and which encodes a putative helix-turn-helix DNA-binding domain. To test the functional significance of this region and determine if this motif is involved in DNA binding, we changed three conserved residues, S210, E213, and R214, to Gly and/or Ala by site-directed mutagenesis. We then isolated and analyzed the five substitution-containing Spo0A proteins for DNA binding and sporulation-specific gene activation. The S210A Spo0A mutant exhibited no change from wild-type binding, although it was defective in spoIIA and spoIIE promoter activation. In contrast, both the E213G and E213A Spo0A variants showed decreased binding and completely abolished transcriptional activation of spoIIA and spoIIE, while the R214G and R214A variants completely abolished both DNA binding and transcriptional activation. These data suggest that these conserved residues are important for transcriptional activation and that the E213 residue is involved in DNA binding.


1991 ◽  
Vol 11 (9) ◽  
pp. 4356-4362 ◽  
Author(s):  
M N Kanaan ◽  
G A Marzluf

cys-3, the major sulfur regulatory gene of Neurospora crassa, activates the expression of a set of unlinked structural genes which encode sulfur catabolic-related enzymes during conditions of sulfur limitation. The cys-3 gene encodes a regulatory protein of 236 amino acid residues with a leucine zipper and an upstream basic region (the b-zip region) which together may constitute a DNA-binding domain. The b-zip region was expressed in Escherichia coli to examine its DNA-binding activity. The b-zip domain protein binds to the promoter region of the cys-3 gene itself and of cys-14, the sulfate permease II structural gene. A series of CYS3 mutant proteins obtained by site-directed mutagenesis were expressed and tested for function, dimer formation, and DNA-binding activity. The results demonstrate that the b-zip region of cys-3 is critical for both its function in vivo and specific DNA-binding in vitro.


1998 ◽  
Vol 72 (2) ◽  
pp. 900-909 ◽  
Author(s):  
Ashok Nambiar ◽  
S. K. Swamynathan ◽  
Jagannadha C. Kandala ◽  
Ramareddy V. Guntaka

ABSTRACT chkYB-2 is a sequence-specific, single-stranded DNA binding chicken Y-box protein that promotes Rous sarcoma virus long terminal repeat (RSV LTR)-driven transcription in avian fibroblasts. The DNA-binding domain of chkYB-2 has been mapped by characterizing the DNA binding properties of purified recombinant chkYB-2 mutant polypeptides. The data indicate that the invariant cold shock domain (CSD) is necessary but not sufficient for association with DNA and suggest that another conserved region, adjacent to the carboxyl boundary of the CSD, plays a role in high-affinity DNA binding. chkYB-2 binds to a tandem repeat of the 5′-GTACCACC-3′ motif on the RSV LTR. Mutational analysis of this recognition sequence revealed the requirement of an essentially unaltered template for both high-affinity binding by chkYB-2 as well as maximal transcriptional activity of the RSV LTR in vivo. The single-stranded DNA binding activity of chkYB-2 is augmented by Mg2+. The possible significance of this finding for transactivation by a single-strand DNA binding protein is discussed.


1999 ◽  
Vol 27 (11) ◽  
pp. 2265-2270 ◽  
Author(s):  
M.-H. David-Cordonnier ◽  
D. Payet ◽  
J.-C. D'Halluin ◽  
M. J. Waring ◽  
A. A. Travers ◽  
...  

2014 ◽  
Vol 42 (20) ◽  
pp. 12523-12536 ◽  
Author(s):  
Sophie S. Nicod ◽  
Robert O. J. Weinzierl ◽  
Lynn Burchell ◽  
Andres Escalera-Maurer ◽  
Ellen H. James ◽  
...  

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