SINP Triennial Report - Saha Institute of Nuclear Physics

Biophysical Sciences Including Chemistry 31
acid sequence of the mature part tallies with the thermostable cysteine protease Ervatamin-C-as was
aimed at. The C-terminal proregion of the protease has altogether a different sequence pattern not
observed in other members of the family and it contains a negatively charged helical zone. The threedimensional
model of the precursor, based on the homology modeling and X-ray structure, show that
the extended peptide stretch region of the N-terminal propeptide, covering the interdomain cleft, contain
protruding side chains of positively charged residues. This study also indicates that the negatively
charged zone of C-terminal propeptide may interact with the positively charged zone of the N-terminal
propeptide in a cooperative manner in the maturation process of this enzyme.
Ghosh, Raka; Dattagupta, Jiban K; Biswas, Sampa
Cell cycle specific expression and nucleolar localization of human J-domain containing co-chaperon
Mrj
J-domain containing co-chaperone Mrj (mammalian relative to DnaJ) has been implicated in diverse
cellular functions including placental development and inhibition of Huntingtin mediated cytotoxicity.
It has also been shown to interact with keratin intermediate filaments. Since keratins undergo extensive
reorganization during cell division, its interactor Mrj might also play an important role in the regulation
of cell cycle. In support of this hypothesis, we report the up-regulation of Mrj protein in M-phase of
HeLa cells implicating its role in mitosis related activities. The protein is dispersed throughout the cell
during late mitosis and is localized in nucleolus during interphase, confirming that the activity of Mrj
is regulated by its cell cycle specific expression together with its differential subcellular localization.
Dey, Sanjib; Banerjee, Paromita; Saha, Partha
mRNA cycling sequence binding protein from Leishmania donovani (LdCSBP) is covalently
modified by ubiquitination
The lack of transcriptional regulation in trypanosomatids suggests the presence of distinct
posttranscriptional mechanisms to control differential gene expression. In fact, the stability of S-phase
specific mRNAs in these parasites is determined primarily by the presence of the octanucleotide sequence
(C/A)AUAGAA(G/A) in the UTRs of the transcripts. Here, the characterization of LdCSBP is reported,
which specifically binds to the octanucleotide containing RNA. The LdCSBP protein contains multiple
putative functional domains, including two types of ubiquitin binding domains (UBA and CUE), two
CCCH-type Zn-finger motifs probably responsible for specific RNA binding activity and a speculative
endonuclease domain SMR. Interestingly, the protein is covalently modified through ubiquitination.
This observation and the occurrence of multiple ubiquitin binding domains in the protein raise the
possibility of regulation of the activity of LdCSBP by ubiquitination.
Bhandari, Dipankar; Saha, Partha
Deregulation and cross talk among Sonic hedgehog, Wnt, Hox and Notch signaling in chronic
myeloid leukemia progression
Deciphering the BCR-ABL-independent signaling exploited in chronic myeloid leukemia (CML)
progression is an important aspect in cancer stem-cell biology. CML stem-cell compartment is dynamic