Gut microbiome. Photo: IBM/Flickr via creative commons

Researchers say they've discovered more than 4,000 new, small protein families generated in the human microbiome, according to a study published Thursday in the journal Cell.

Why it matters: The human microbiome is thought to help maintain health but also is linked to obesity-related cancers, Alzheimer's and how cancer therapies work. The function of these newly found tiny proteins still needs to be determined, but the authors believe their size could allow them to be leveraged to deliver drugs.

"Some of these proteins may also be small enough to synthesize and use as possible drug-like molecules, especially if they have potentially beneficial functions such as targeted and selective antimicrobial activity, or the ability to signal to human host cells."
— Ami Bhatt, senior author from Stanford, to Axios

What they did: Over a 4-year period, the team collected large amounts of microbiome data from humans, animals and the environment and sequenced their DNA.

  • They compared 1,773 metagenomes from four different sites on the body and developed "filters" to identify possible human-associated genes and then tested if the genes encoded true proteins.

What they found: They discovered more than 4,000 protein families, 90% of which have no known function and almost half have not been previously catalogued.

  • They estimate 30% of the proteins may be involved in cell-to-cell communication.
  • While not yet tested, Bhatt says "these proteins likely play important roles in biology, ranging from antimicrobial activity to being regulators of cell-surface signaling systems and transporters."

What they're saying: Nicola Segata, associate professor and principal investigator at University of Trento's Centre for Integrative Biology, tells Axios the study offers a first, "crucial step" in linking small microbiome proteins with human diseases by identifying and cataloging them.

  • But, "it is premature to speculate on whether and how this discovery will be relevant for future therapies," adds Segata, who was not part of this study.

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