The chloroplast SRP systems of chaetosphaeridium globosum and physcomitrella patens as intermediates in the evolution of SRP-dependent...

 

Ziehe D, Dünschede B, Zenker M, Funke S, Nowaczyk M, Schünemann D,

PLoS ONE
2016 vol: 11 (11) pp: 1-18

Abstract

The bacterial signal recognition particle (SRP) mediates the cotranslational targeting of membrane proteins and is a high affinity complex consisting of a SRP54 protein subunit (Ffh) and an SRP RNA. The chloroplast SRP (cpSRP) pathway has adapted throughout evolution to enable the posttranslational targeting of the light harvesting chlorophyll a/b binding proteins (LHCPs) to the thylakoid membrane. In spermatophytes (seed plants), the cpSRP lacks the SRP RNA and is instead formed by a high affinity interaction of the conserved 54-kD subunit (cpSRP54) with the chloroplast-specific cpSRP43 protein. This heterodimeric cpSRP recognizes LHCP and delivers it to the thylakoid membrane. However, in contrast to spermatophytes, plastid SRP RNAs were identified within all streptophyte lineages and in all chlorophyte branches. Furthermore, it was shown that cpSRP43 does not interact with cpSRP54 in chlorophytes (e.g., Chlamydomonas reinhardtii). In this study, we biochemically characterized the cpSRP system of the charophyte Chaetosphaeridium globosum and the bryophyte Physcomitrella patens. Interaction studies demonstrate low affinity binding of cpSRP54 to cpSRP43 (Kd ~10 μM) in Chaetosphaeridium globosum and Physcomitrella patens as well as relatively low affinity binding of cpSRP54 to cpSRP RNA (Kd ~1 μM) in Physcomitrella patens. CpSRP54/cpSRP43 complex formation in charophytes is supported by the finding that specific alterations in the second chromodomain of cpSRP43, that are conserved within charophytes and absent in land plants, do not interfere with cpSRP54 binding. Furthermore, our data show that the elongated apical loop structure of the Physcomitrella patens cpSRP RNA contributes to the low binding affinity between cpSRP54 and the cpSRP RNA.

View Publication

Topics: Fusion proteins, Measure binding affinity, Monolith – Microscale Thermophoresis, Nucleic acids DNA, Plant proteins, Proteins, Publications

 

 

Previous Article
Reconstitution of a mycobacterium tuberculosis proteostasis network highlights essential cofactor interactions with chaperone DnaK
Reconstitution of a mycobacterium tuberculosis proteostasis network highlights essential cofactor interactions with chaperone DnaK

Up next
Structure and function of cyanobacterial DHDPS and DHDPR
Structure and function of cyanobacterial DHDPS and DHDPR

×

Sign up to receive
the latest NanoTemper news, product updates, event announcements and more

First Name
Last Name
Company Name
State
Province
State
Region
State
Canton
Agree to Privacy Policy*
*I have fully read, understood and agree to the Privacy Policy. I accept the storing and processing of my personal data by NanoTemper as described in the Privacy Policy.

By completing this form, you provide us consent to contact you with educational content, news and information about our products, services and events. You may unsubscribe at any time.
Thank you!
Error - something went wrong!