Related Experiment Video
Updated: May 3, 2026
13:30
A New Screening Method for the Directed Evolution of Thermostable Bacteriolytic Enzymes
Published on: November 7, 2012
18.4K
Combining Signal Peptide Optimization with Directed Evolution to Enhance Chitosanase Activity.
Yao Chen1, Min Chen1, Xinli Lin1
1Taizhou Key Laboratory of Biomass Functional Materials Development and Application, School of Life Science, Taizhou University, Taizhou 318000, China.
Journal of Agricultural and Food Chemistry
|December 17, 2025
Summary
Directed evolution enhanced chitosanase performance by engineering its signal peptide for better screening. This led to the M8 variant with 10-fold higher activity and improved substrate affinity.
Area of Science:
- Enzymology
- Protein Engineering
- Biotechnology
Background:
- Directed evolution is key for enzyme improvement but often limited by screening.
- Chitosanase enzymes are crucial for degrading chitosan, with applications in various industries.
- Efficient screening is vital for identifying high-performance enzyme variants.
Purpose of the Study:
- To develop an efficient screening system for directed evolution of chitosanase.
- To engineer the signal peptide of Bacillus subtilis chitosanase (Csn168) to improve screening.
- To discover novel chitosanase variants with enhanced catalytic activity and substrate affinity.
Main Methods:
- Site-saturation mutagenesis of the Csn168 signal peptide to attenuate secretion.
- Iterative directed evolution coupled with hydrolytic zone screening.
- Biochemical characterization and molecular dynamics simulations of enzyme variants.
Main Results:
- Engineered signal peptide enabled high-resolution screening based on hydrolytic zone formation.
- Identified the M8 variant with a 10-fold increase in catalytic activity and 28 mm hydrolytic zone in 33 h.
- M8 variant exhibited enhanced substrate affinity (Km reduced from 25.56 to 11.75 g/L) and faster catalytic turnover.
Conclusions:
- Coupling signal peptide engineering with directed evolution is an effective strategy for rapid discovery of high-performance enzymes.
- The engineered M8 variant shows significant potential for industrial applications requiring efficient chitosan degradation.
- This approach provides a robust platform for optimizing other enzyme families through directed evolution.
Related Concept Videos
01:15Amplifying Signals via Second Messengers
6.1K
Many receptor binding ligands are hydrophilic; they do not cross the cell membrane but bind to cell-surface receptors. Thus, their message must be relayed by second messengers present in the cell cytoplasm. There are several second messenger pathways, each with its own way of relaying information. For example, the G protein-coupled receptors can activate both phosphoinositol and cyclic AMP (cAMP) second messenger pathways. The phosphoinositol pathway is active when the receptor induces...
6.1K
01:22Amplifying Signals via Enzymatic Cascade
15.3K
When a ligand binds to a cell-surface receptor, the receptor's intracellular domain changes shape, which may either activate its enzyme function or allow its binding to other molecules. The initial signal is amplified by most signal transduction pathways. This means that a single ligand molecule can activate multiple molecules of a downstream target. Proteins that relay a signal are most commonly phosphorylated at one or more sites, activating or inactivating the protein. Kinases catalyze...
15.3K
01:28Nitric Oxide Signaling Pathway
5.3K
Nitric oxide (NO), an inorganic gas, acts as a potent second messenger in most animal and plant tissues. NO diffuses out of the cells that produce it and enters the neighboring cells to generate a downstream response. NO synthase (NOS) catalyzes NO production by the deamination of the amino acid arginine. There are three isoforms of NOS. Endothelial cells have endothelial NOS (eNOS), nerve and muscle cells have neuronal NOS (nNOS), and macrophages produce inducible NOS (iNOS) upon exposure...
5.3K
01:24Tagging and Fusion Proteins
6.4K
Proteins are involved in several cellular processes and biochemical reactions. Analyzing a specific protein of interest requires it to be isolated from the other proteins in the cell. This is achieved by overexpressing the specific gene in a suitable host to produce large quantities of the target protein. A tag or label is recombined with the gene to produce a fusion protein containing the target protein and the tag. The tags on these fusion proteins can then be used for easy detection and...
6.4K
01:26Signal Transduction: Overview
8.6K
Cells respond to many types of information, often through receptor proteins positioned on the membrane. They respond to chemical signals, such as hormones, neurotransmitters, and other signaling molecules, initiating a series of molecular reactions to produce an appropriate response. This is called signal transduction. Cells also coordinate different responses elicited by the same signaling molecule via mediators, allowing molecular cross-talk.
Typically, signal transduction involves three...
Typically, signal transduction involves three...
8.6K
01:27Transducer Mechanism: Enzyme-Linked Receptors
4.4K
Enzyme-linked receptors are cell-surface receptors acting as an enzyme or associating with an enzyme intracellularly. They make excellent drug targets. Drugs can bind to the extracellular ligand-binding domain or directly affect their enzymatic domain and alter their activity.
Major types that are helpful drug targets include:
Major types that are helpful drug targets include:
4.4K