They say if they are right, their research could be used to produce silk in the laboratory for extra-strong protective clothing, sporting equipment and even replacement tissue.
Silk is the strongest natural fibre known but scientists have not been able to replicate its strength.
They have managed to purify silk into powder but have not been able to turn it into material.
“The problem is that when people take these purified powders and try to make useful materials they fall well short,” said David Kaplan, professor of biomedical engineering at Tufts University in Massachusetts.
Kaplan and his team say the secret to silk production lies in how spiders and silkworms control silk protein solubility in their glands.
“The entire process is controlled by the amount of water, which is so simple,” he said.
“The organism dumps protein into the gland but as it does that, it regulates how much water it leaves in there. That controls the entire process."
The research, published in this week’s edition of science journal Nature, could have far-reaching applications, including in medicine.
Bioengineers at Tufts have already developed a strategy for using silk to repair damaged knee ligaments and say it could be used to make artificial bone tissue.