Book Review 1115

The coming of age of biological electron microscopyRichard Henderson

Address: MRC Laboratory of Molecular Biology, Hills Road,Cambridge CB2 2QH, UK.

E-mail: rh15@mrc-lmb.cam.ac.uk

Structure 15 September 1996, 4:1115–1116

© Current Biology Ltd ISSN 0969-2126

Three-dimensional electron microscopy of macromolecu-

lar assemblies by Joachim Frank, Academic Press, 1996, 360pages, $85.00 hardback (ISBN 0-12-265040-9).

Towards the end of the century, the growth in power andspeed of the three major techniques of macromolecular-structure determination shows no sign of slackening.There is not yet an example of an atomic structure of abiological molecule independently determined by allthree methods of X-ray crystallography, nuclear magneticresonance (NMR) and electron microscopy, but there is considerable convergence. For individual, smaller,protein molecules and occasionally complexes, structuresare now frequently determined successfully by bothX-ray diffraction and NMR, though each method has itsrealm of dominance. For large macromolecular assem-blies such as viruses, a low resolution-structure analysisby three-dimensional electron microscopy is frequentlyfollowed by a high resolution X-ray crystal structuredetermination. In a small number of cases, atomicmodels of membrane proteins have been derived byelectron microscopy alone. With rapid progress beingmade in all three methods, it cannot be long before thesame structure is determined independently by all three.There is however, a unique dearth of books treating theelectron microscopy of biological molecules. JoachimFrank’s new book Three-dimensional Electron Microscopy ofMacromolecular Assemblies now puts this right. Frank’sbook does not attempt the global dominance aimed forby Wuthrich’s NMR of Proteins and Nucleic Acids nor thefinely structured comprehensive coverage of Blundelland Johnson’s Protein Crystallography but instead intro-duces the subject from the author’s rich personal per-spective. Frank’s background and experience are in thetheory of image formation in electron microscopy, thedevelopment of mathematical methods for computer-based image processing in two and three dimensions andtheir application at increasingly higher resolution to thestructure determination of macromolecular assemblies,especially the ribosome. A beautiful three-dimensionalmulticoloured representation of the E. coli ribosome inthe act of translating an RNA message into a growingpolypeptide is shown on the cover, derived using themethods described in the following 300 pages.

Between the covers, the text explains clearly all the jargonand keywords necessary for entry to the brotherhood of bio-logical electron microscopy. It contains a modicum of math-ematics, in just about the right dose for biologists. Frankhas a tendency to blur over critical problems by wordy defi-nitions and philosophical musing, but this adds to theunique and attractive character of the book.

On the technical side, the presentation is slanted towardsimage-analysis methods which involve classification, prin-cipal-component analysis and multivariate statistics. Thereis a strong emphasis on mathematical power as the domi-nant approach to overcoming the physical imperfections ofthe images. As in a Simenon detective story, realityemerges from the clues that are disentangled throughphilosophically oriented mathematical exploration.

The discussion of the improvements in resolution attainedduring the development of the field, from the negativelystained specimens of the 1960s through to the unstained,ice-embedded procedures introduced by Dubochet and hiscolleagues in the 1980s, is well covered. There are excel-lent in-depth explanations of the various resolution criteria(differential phase residual [DPR], Fourier ring correlation[FRC], ratio of moduli of vectorial sum to sum of moduli ofcontributing structure factors [Q factor]) adopted by differ-ent factions, as well as rehearsals of earlier, illuminatingarguments and controversies. Frank himself seems undulypessimistic about the long-term possibilities for atomic res-olution single-particle structure determinations of macro-molecular assemblies, or ‘crystallography without crystals’as he calls it. He does not mention the possibility of restor-ing the power of high resolution Fourier components,which are greatly reduced at the outer resolution limit ofany analysis by simply ‘sharpening’ the data. Instead, heemphasizes the very small power content at the outer reso-lution boundary and seems to suggest that such mea-surements, which are statistically absolutely reliable, aresomehow less valuable because they are weak in theimage: there is no mention that a restoration of the originalpower can be done by simple multiplication.

The book is nevertheless a wonderful, coherent and satis-fying introduction to the field. Its publication adds to theunderlying framework of structures supporting the fieldwhich now boasts its own Gordon Conference series Three-dimensional EM of Macromolecules held every two years (thenext meeting is in 1997); its own e-mail mailing list3dem@mcrcr6.med.nyu.edu (to subscribe, send ‘subscribe3dem’ to mailserv@mcrcr.med.nyu.edu), a 3dem web pagehttp://rcr-www.med.nyu.edu/3dem; and a recent specialissue of Journal of Structural Biology (

116, 1–249 [1996])

with 33 articles describing all of the currently availablesoftware in the field. Amongst these, there is an article onthe SPIDER/WEB system that Frank’s group has pio-neered, which is used for most of the illustrations in thebook. This book should be a compulsory addition to theshelves of all those structural biologists who aim for awider understanding of the methods of macromolecularstructure determination.

1116 Structure 1996, Vol 4 No 9