Biophysical characterizations of human mitochondrial transcription factor A and its binding to tumor suppressor p53.
Human mitochondrial transcription factor A (TFAM) is a multi-functional protein, involved in different aspects of maintaining mitochondrial genome integrity. In this report, we characterized TFAM and its interaction with tumor suppressor p53 using various biophysical methods. DNA-free TFAM is a thermally unstable protein that is in equilibrium between monomers and dimers. Self-association of TFAM is modulated by its basic C-terminal tail. The DNA-binding ability of TFAM is mainly contributed by its first HMG-box, while the second HMG-box has low-DNA-binding capability. We also obtained backbone resonance assignments from the NMR spectra of both HMG-boxes of TFAM. TFAM binds primarily to the N-terminal transactivation domain of p53, with a K(d) of 1.95 +/- 0.19 microM. The C-terminal regulatory domain of p53 provides a secondary binding site for TFAM. The TFAM-p53-binding interface involves both TAD1 and TAD2 sub-domains of p53. Helices alpha1 and alpha2 of the HMG-box constitute the main p53-binding region. Since both TFAM and p53 binds preferentially to distorted DNA, the TFAM-p53 interaction is implicated in DNA damage and repair. In addition, the DNA-binding mechanism of TFAM and biological relevance of the TFAM-p53 interaction are discussed.
Wong
Tuck Seng
TS
MRC Centre for Protein Engineering, Medical Research Council, Hills Road, Cambridge CB2 0QH, UK.
Rajagopalan
Sridharan
S
Freund
Stefan M
SM
Rutherford
Trevor J
TJ
Andreeva
Antonina
A
Townsley
Fiona M
FM
Petrovich
Miriana
M
Fersht
Alan R
AR
D002460:Cell Line; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D024243:HMGB1 Protein / Q000378:metabolism; D024261:HMGB2 Protein / Q000378:metabolism; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D024101:Mitochondrial Proteins / Q000737:chemistry / Q000378:metabolism*; D055503:Protein Multimerization; D017434:Protein Structure, Tertiary; D014157:Transcription Factors / Q000737:chemistry / Q000378:metabolism*; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*
D004268:DNA-Binding Proteins; D024243:HMGB1 Protein; D024261:HMGB2 Protein; D024101:Mitochondrial Proteins; D014157:Transcription Factors; D016159:Tumor Suppressor Protein p53; C422562:mitochondrial transcription factor A