The germ line produces gametes that transmit genetic and epigenetic information to the next generation. Maintenance of germ cells and development of gametes require germ granules—well-conserved membraneless and RNA-rich organelles. The composition of germ granules is elusive owing to their dynamic nature and their exclusive expression in the germ line. Using C. elegans germ granule, called P granule, as a model system, we employed a proximity-based labeling method in combination with mass spectrometry to comprehensively define its protein components. This set of experiments identified over 200 proteins, many of which contain intrinsically disordered regions. An RNAi-based screen identified factors that are essential for P granule assembly, notably EGGD-1 and EGGD-2, two putative LOTUS-domain proteins. Loss of eggd-1 and eggd-2 results in separation of P granules from the nuclear envelope, germline atrophy and reduced fertility. We show that intrinsically disordered regions of EGGD-1 are required to anchor EGGD-1 to the nuclear periphery while its LOTUS domains are required to promote perinuclear localization of P granules. Together, our work expands the repertoire of P granule constituents and provides new insights into the role of LOTUS-domain proteins in germ granule organization.

See details in Materials and Methods

File "Figure 1-Source Data 1" Source data file for Figure 1B.

File "Figure 1-Source Data 2-uncropped_blot_images.zip" for uncropped blots of Figure 1C.

File "Figure 1-figure supplement 1-Source data 1-uncropped_blot_images.zip" for uncropped blots of Figure 1—figure supplement 1B.

File "Figure 2-Source Data 1" Source data file for Figure 2A.

File "Figure 2-Source Data 2" Source data file for Figure 2E and Figure 2F.

File "Figure 3-Source Data 1" Source data file for Figure 3D.

File "Figure 3-Source Data 2" Source data file for Figure 3E.

File "Figure 3-Source Data 3" Source data file for Figure 3F.

File "Figure 3-Supplement 1-Source Data 1" Source data file for Figure 3-Supplement 1E.

File "Figure 4-Source Data 1" Source data file for Figure 4A and 4B.

File "Figure 4-Source Data 2" Source data file for Figure 4E.