细菌粘膜的秘密

Newcastle University scientists have revealed the mechanism¹ that causes a slime（黏液，烂泥） to form, making bacteria hard to shift and resistant² to antibiotics³. When under threat, some bacteria can shield themselves in a slimy（黏滑的） protective layer, known as a biofilm. It is made up of communities of bacteria held together to protect themselves from attack.

 

Biofilms cause dental plaque⁴（菌斑，牙垢） and sinusitis（窦炎）; in healthcare, biofilms can lead to life threatening and difficult to treat infections, particularly on medical implants⁵ such as catheters（导尿管）, heart valves, artificial hips⁶ and even breast implants. They also they coat the outside of ships and boats polluting the water.

 

Publishing in the Journal of Biological Chemistry, the team reveal how a molecular⁷ switch regulates biofilm formation. This new understanding could help identify a new target for antibiotics and prevent other biofilms from forming.

 

In order to thwart⁸ them from causing disease and biopollution, a Newcastle University team have been studying at the molecular level how bacteria form biofilms in the first instance.

 

They reveal how the master regulator of biofilm formation, a protein called SinR, acts in the model bacterium⁹, Bacillus subtilis.

 

Richard Lewis, Professor of Structural¹⁰ Biology in the Institute for Cell and Molecular Biosciences who led the research said: "SinR is a bit like a rocker switch, a domestic light switch for instance. In the "down" position, when SinR is bound to DNA¹¹, the proteins required to make a biofilm are turned off and the bacteria are free to move. In the "up" position, SinR is no longer bound to DNA and instead interacts with other proteins, and the biofilms genes¹² are turned on."

 

SinR is a DNA-binding protein that acts to inhibit¹⁴ the expression of proteins required for the synthesis of the molecular glue that holds the biofilm together. The ability of SinR to bind¹³ to DNA is carefully controlled by a network of interactions with three other proteins. By the application of X-ray crystallography, the team have determined¹⁵ precisely¹⁶ how SinR interacts with very specific feature of its DNA target.

 

By understanding how the proteins interact with each other, and with DNA, scientists can look to develop molecules¹⁷ that interfere¹⁸ with these essential processes as a means to stop biofilms from forming.

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