Proton-guided movements of tRNA within the Leishmania mitochondrial RNA import complex
IR@IICB: CSIR-Indian Institute of Chemical Biology, Kolkata
View Archive Info| Field | Value | |
| Title |
Proton-guided movements of tRNA within the
Leishmania mitochondrial RNA import complex
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| Creator |
Basu, Sudarshana
Mukherjee, Saikat Adhya, Samit |
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| Subject |
Molecular & Human Genetics
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| Description |
The RNA import complex (RIC) from the mitochondrion
of the kinetoplastid protozoan Leishmania
tropica contains two subunits that directly bind to
import signals on two distinct subsets of tRNA and
interact with each other allosterically. What happens
to the tRNA subsequent to its loading on the
complex is unknown. A third subunit—RIC9—has
intrinsic affinity for both types of tRNA and is
essential for import in vivo. Here we show that
antibody against RIC9 inhibited the import of both
types of tRNA into mitoplasts in vitro, but failed to
inhibit the binding of these tRNAs to their respective
receptors, indicating that RIC9 acts in a subsequent
step. Using photoaffinity crosslinking-immunoprecipitation
to detect translocation intermediates, it
was observed that tRNA was transferred from its
cognate receptor to RIC9, followed by translocation
across the membrane and release as free tRNA in
the inner compartment. Transfer required elevated
temperatures and ATP, but ATP was substituted by
acid pH. These tRNA movements were sensitive to
uncouplers and inhibitors, suggesting distinct roles
of the electrical and chemical components of the
proton motive force generated by vectorial proton
translocation accompanying ATP hydrolysis. By
analysis of partially assembled complexes in
L. tropica depleted of various subunits, and in vitro
assembly assays, RIC9 was shown to make stable
contacts with RIC8A, a tRNA receptor and RIC6, a
membrane-embedded component. The results have
implications for the mechanism of tRNA import.
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| Date |
2008
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| Type |
Article
PeerReviewed |
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| Format |
application/pdf
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| Identifier |
http://www.eprints.iicb.res.in/190/1/NUCLEIC_ACIDS_RESEARCH%2C36(_5)%2C1599%2D1609%2C2008[117].pdf
Basu, Sudarshana and Mukherjee, Saikat and Adhya, Samit (2008) Proton-guided movements of tRNA within the Leishmania mitochondrial RNA import complex. Nucleic Acids Research, 36 (5). pp. 1599-1609. |
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| Relation |
http://dx.doi.org/10.1093/nar/gkn010
http://www.eprints.iicb.res.in/190/ |
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