Conformational Ensembles from Experimental Data
and Computer Simulations
Poster Abstracts
95
60-POS
Board 20
Elucidating Structure and Conformational Changes with Cross-Linking/Mass
Spectrometry (CLMS)
Michael Schneider
2
,
Mahmoud Mabrouk
1
, Kolja Stahl
1
, Oliver Brock
1
, Juri Rappsilber
3,2
.
1
Technische Universität Berlin, Berlin, Germany,
2
Technische Universität Berlin, Berlin,
Germany,
3
University of Edinburgh, Edinburgh, United Kingdom.
Protein structure and dynamics are studied typically outside the native context needed for correct
function and possibly also folding. Cross-linking/mass spectrometry (CLMS) is a maturing
structure analysis tool, poised to overcome this limitation. Under native conditions, cross-linkers
can convert proximity into chemical bridges that can be observed experimentally. CLMS can
reveal the structure of individual proteins, probe protein assemblies, and deliver proteome-wide
information. Our labs recently added novel chemistry to drastically improve the density of data
obtained.
Leveraging CLMS data computationally remains challenging since it contains noise and
averaged data. We recently demonstrated that using high-density CLMS data, which increases
the amount of cross-links by an order of magnitude, enables the de novo reconstruction of the
human serum albumin domains. The key to this success is the complementary integration of
experiment and computation: We were able to utilize CLMS data with a degree of noise that
would normally be rejected using a noise intolerant conformational space search algorithm. Our
method is novel in two key aspects: first, it models cross-link constraints with a modified
Lorentz function allowing it to be robust to wrongly predicted cross-links. Second, it leverages
cross-links to guide the search towards promising regions which are then searched using an
unbiased all-atom energy function.
Combining high-density cross-linking with quantitative experimental setups hold a high potential
to elucidate protein dynamics. We have recently made use of CLMS to reveal subtle
conformational changes in the complement protein C3 and its activated cleavage product C3b.
Yet, the development of computational methods for interpreting this data is still in its early
stages. We see the upcoming conference as an ideal chance to disseminate our findings to a panel
of experts and discuss the future of this novel type of experimental data.