  Multi-step assembly of individual protein building blocks is key to the
formation of essential higher-order structures inside and outside of cells.
Optical tweezers is a technique well suited to investigate the mechanics and
dynamics of these structures at a variety of size scales. In this mini-review,
we highlight experiments that have used optical tweezers to investigate protein
assembly and mechanics, with a focus on the extracellular matrix protein
collagen. These examples demonstrate how optical tweezers can be used to study
mechanics across length scales, ranging from the single-molecule level to
fibrils to protein networks. We discuss challenges in experimental design and
interpretation, opportunities for integration with other experimental
modalities, and applications of optical tweezers to current questions in
protein mechanics and assembly.
