Mainly on the Plane: Deep Subsurface Bacterial Proteins Bind and Alter Clathrate Structure

Area of Science:

• Biochemistry
• Materials Science
• Environmental Science

Background:

• Gas clathrates present both opportunities as natural gas storage and challenges due to pipeline blockages.
• Controlling gas clathrate formation requires eco-friendly technologies.
• Type I Antifreeze Proteins (AFPs) bind to gas clathrates, influencing their growth.

Purpose of the Study:

• To investigate if bacterial proteins from natural gas clathrate environments bind to and modify clathrate morphology.
• To identify and characterize potential clathrate-binding proteins (CBPs) from native bacterial genomes.

Main Methods:

• Bioinformatic analysis of metagenomes from natural clathrate deposits to identify putative clathrate-binding proteins (CBPs).
• Recombinant expression and purification of five CbpA proteins.
• Experimental binding assays using tetrahydrofuran (THF) clathrate, a model for structure II gas clathrate.

Main Results:

• Four of the five purified CbpA proteins were stable and demonstrated binding to THF clathrate.
• The presence of CbpAs resulted in polycrystalline, platelike THF clathrate instead of single octahedral crystals.
• Two CbpAs induced branching clathrate crystals, while two others formed hexagonal crystals, indicating distinct binding modes.

Conclusions:

• Bacterial clathrate-binding proteins (CBPs) can bind to gas clathrates and alter their crystal morphology.
• These findings suggest potential industrial applications for bacterial CBPs in controlling gas clathrate structures, particularly for pipeline transportation.