Related Experiment Video
Updated: May 18, 2026
10:05
Studying RNA Interactors of Protein Kinase RNA-Activated during the Mammalian Cell Cycle
Published on: March 5, 2019
Rigidifying acyl carrier protein domain in iterative type I PKS CalE8 does not affect its function.
Jackwee Lim1, Huihua Sun, Jing-Song Fan
1Department of Biological Sciences, National University of Singapore, Singapore.
Biophysical Journal
|September 27, 2012
Summary
Acyl carrier protein (ACP) domains are crucial for fatty acid and polyketide synthesis. This study reveals that internal dynamics of ACP helical regions are not critical for function, challenging previous beliefs.
Area of Science:
- Biochemistry
- Molecular Biology
- Structural Biology
Background:
- Acyl carrier protein (ACP) domains are essential components of fatty acid synthase (FAS) and polyketide synthase (PKS) systems.
- ACPs function as shuttles for acyl intermediates between catalytic domains.
- The precise role of protein dynamics in ACP function remains incompletely understood.
Purpose of the Study:
- To investigate the role of protein dynamics in the function of ACP domains within iterative type I PKS.
- To determine if millisecond-second timescale dynamics are critical for ACP-mediated acyl transfer.
Main Methods:
- Nuclear Magnetic Resonance (NMR) spectroscopy was employed to study the dynamics of the CalE8 ACP domain.
- Site-directed mutagenesis was used to introduce an interhelical disulfide linkage to rigidify the ACP domain.
- Functional assays were performed on the full-length PKS with the modified ACP domain.
Main Results:
- The ACP domain of iterative type I PKS CalE8 exhibits significant dynamics on the millisecond-second timescale.
- Introducing a disulfide linkage to rigidify the ACP domain suppressed millisecond-second dynamics and reduced picosecond-nanosecond mobility.
- The full-length PKS remained fully functional even after rigidification of its ACP domain.
Conclusions:
- The internal dynamics of the helical regions within ACP domains are not critical for the function of iterative type I PKS.
- Flexibility in disordered terminal linkers, rather than internal helical dynamics, may be more important for ACP function.
- These findings refine our understanding of the structural and dynamic requirements for acyl carrier protein activity in PKS systems.
More Related Videos
Related Concept Videos
01:19Allosteric Proteins-ATCase
Binding sites linkages can regulate a protein's function. For example, enzyme activity is often regulated through a feedback mechanism where the end product of the biochemical process serves as an inhibitor.
Aspartate transcarbamoylase (ATCase) is a cytosolic enzyme that catalyzes the condensation of L-aspartate and carbamoyl phosphate to N-carbamoyl-L-aspartate. This reaction is the first step in pyrimidine biosynthesis. UTP and CTP, the end products of the pyrimidine synthesis pathway,...
Aspartate transcarbamoylase (ATCase) is a cytosolic enzyme that catalyzes the condensation of L-aspartate and carbamoyl phosphate to N-carbamoyl-L-aspartate. This reaction is the first step in pyrimidine biosynthesis. UTP and CTP, the end products of the pyrimidine synthesis pathway,...
01:09GPCRs Regulate Adenylyl Cylase Activity
Some GPCRs transmit signals through adenylyl cyclase (AC), a transmembrane enzyme. AC helps synthesize second messenger cyclic adenosine monophosphate (cAMP). AC catalyzes cyclization reaction and converts ATP to cAMP by releasing a pyrophosphate. The pyrophosphate is further hydrolyzed to phosphate by the enzyme pyrophosphatase, which drives cAMP synthesis to completion. However, cAMP is rapidly degraded to 5′ AMP by the enzymes phosphodiesterase (PDE), preventing overstimulation of cells.
Two...
Two...
02:04Covalently Linked Protein Regulators
Proteins can undergo many types of post-translational modifications, often in response to changes in their environment. These modifications play an important role in the function and stability of these proteins. Covalently linked molecules include functional groups, such as methyl, acetyl, and phosphate groups, and also small proteins, such as ubiquitin. There are around 200 different types of covalent regulators that have been identified.
These groups modify specific amino acids in a protein.
These groups modify specific amino acids in a protein.
01:16Calmodulin-dependent Signaling
Calmodulin (CaM) is a calcium-binding protein in eukaryotes that controls various calcium-regulated cellular processes. It has four calcium-binding sites that bind calcium to form the calcium-calmodulin ( Ca2+-CaM) complex. GPCR stimulation increases the calcium levels in the cells that bind to CaM and induces a conformational change.
The Ca2+-CaM complex does not have enzymatic activity by itself. Instead, the complex binds downstream target proteins, including membrane proteins or enzymes,...
The Ca2+-CaM complex does not have enzymatic activity by itself. Instead, the complex binds downstream target proteins, including membrane proteins or enzymes,...
02:18Intrinsically Disordered Proteins
Intrinsically disordered proteins are a group of proteins that do not fold into specific three-dimensional structures. Their structural flexibility allows them to complement ordered proteins to perform functions that are inaccessible to rigid structures. They are more common in eukaryotes than prokaryotes and may either be exclusively intrinsically disordered or hybrid proteins, consisting of a mix of ordered and disordered regions. The absence of a rigid structure in these proteins can be...
01:37The Unfolded Protein Response
The ER is the hub of protein synthesis in a cell. It has robust systems to quality control protein folding and also for degradation of terminally misfolded proteins. Under normal conditions, a small proportion of misfolded proteins that cannot be salvaged need to be transported to the cytoplasm by the ER-associated degradation or ERAD pathways. However, if the ERAD cannot handle the misfolded proteins, the cell activates the unfolded protein response or UPR to adjust the protein folding...