Flowering is controlled by cis trans switches Flashcards
What are the phi and psi angles of rotation around each peptide group responsible for?
The three-dimensional conformation of a polypeptide backbone is defined by the φ (phi) and ψ (psi) angles of rotation around each peptide group.
KEY CONCEPT
What is the favored conformation of peptide groups during protein synthesis?
Almost all peptide groups adopt the trans conformation since that is the one favored during protein synthesis.
BOX 4.1 FLOWERING IS CONTROLLED BY CIS/TRANS SWITCHES
What is the exception to the rule of peptide groups adopting the trans conformation?
The change in peptide group conformation invariably takes place at proline residues because the cis conformation is almost as stable as the trans conformation. This is the one exception to the rule.
BOX 4.1 FLOWERING IS CONTROLLED BY CIS/TRANS SWITCHES
What is the role of peptidyl prolyl cis/trans isomerases in regulating protein conformation?
Specific enzymes, called peptidyl prolyl cis/trans isomerases, catalyze the interconversion of cis and trans conformation at proline residues by transiently destabilizing the resonance hybrid structure of the peptide bond and allowing rotation.
BOX 4.1 FLOWERING IS CONTROLLED BY CIS/TRANS SWITCHES
What is the role of Pin1 in regulating gene expression?
In humans, the cis/trans isomerase encoded by Pin1 plays a role in regulating gene expression by modifying RNA polymerase, transcription factors, and other proteins.
BOX 4.1 FLOWERING IS CONTROLLED BY CIS/TRANS SWITCHES
What is the significance of the Pin1 gene in Arabidopsis thaliana?
In the small flowering plant, Arabidopsis thaliana, Pin1 protein acts on some transcription factors that control the timing of flowering. When threonine residues are phosphorylated, the transcription factors are recognized by Pin1 and the conformation of the Thr-Pro bond is switched from trans to cis.
BOX 4.1 FLOWERING IS CONTROLLED BY CIS/TRANS SWITCHES
